Molecular characterization of mucopolysaccharidosis type IVA patients in the Andean region of Colombia.

Colombia has a high prevalence of mucopolysaccharidosis (MPS) type IVA. Nevertheless, data regarding the mutation spectrum for MPS IVA in this population have not been completely characterized. Forty-seven families and 53 patients from seven different Colombian regions were tested for MPS IVA mutations. We compared the sequences with the N-acetylgalactosamine-6-sulfatase (GALNS) reference sequence NM_000512.4, and gene variants were reported. Bioinformatics analysis was performed using SWISS-MODEL. The mutant proteins were generated by homology from the wild-type GALNS 4FDJ template obtained from the PDB database, and visualization was performed using Swiss-PDBViewer and UCSF Chimera. The predictive analysis was run using different bioinformatic tools, and the deleterious annotation of genetic variants was performed using a neural network. We found that 79% and 21% of the cohort was homozygous and compound heterozygous, respectively. The most frequent mutation observed was p.Gly301Cys (78.3% of alleles), followed by p.Arg386Cys (10.4% of alleles). A novel mutation (p.Phe72Ile) was described and classified in silico as a pathogenic variant. This study reveals the mutation spectrum of MPS IVA in Colombia. The high prevalence of the p.Gly301Cys mutation suggests a founder effect of this variant in the Colombian population that causes diseases in the Andean region (via migration). These data can facilitate genetic counseling, prenatal diagnosis, and the design of therapeutic interventions.

Novel progressive acrodysostosis-like skeletal dysplasia, cerebellar atrophy, and ichthyosis.

Acrodysostosis refers to a rare heterogeneous group of bone dysplasias that share skeletal features, hormone resistance, and intellectual disability. Two genes have been associated with acrodysostosis with or without hormone resistance (PRKAR1A and PDE4D). Severe intellectual disability has been reported with acrodysostosis but brain malformations and ichthyosis have not been reported in these syndromes. Here we describe a female patient with acrodysostosis, intellectual disability, cerebellar hypoplasia, and lamellar ichthyosis. The patient has an evolving distinctive facial phenotype and childhood onset ataxia. X-rays showed generalized osteopenia, shortening of middle and distal phalanges, and abnormal distal epiphysis of the ulna and radius. Brain magnetic resonance imaging showed cerebellar atrophy without other brainstem abnormalities. Genetic workup included nondiagnostic chromosomal microarray and skeletal dysplasia molecular panels. These clinical findings are different from any recognized form of acrodysostosis syndrome. Whole exome sequencing did not identify rare or predicted pathogenic variants in genes associated with known acrodysostosis, lamellar ichthyosis, and other overlapping disorders. A broader search for rare alleles absent in healthy population databases and controls identified two heterozygous truncating alleles in FBNL7 and PPM1M genes, and one missense allele in the NPEPPS gene. Identification of additional patients is required to delineate the mechanism of this unique disorder.

Male patient 46,XX SRY-negative and unambiguous genitalia: A case report / Paciente masculino con cariotipo 46 XX negativo para el gen SRY y sin ambigüedad genital: reporte de un caso

In most cases, male sexual differentiation occurs with SRY gene mediation. However, exceptional genotypes have been identified, as shown in this paper. This was a male adult patient seen at the Servicio de Paternidades, Instituto de Genética, Universidad Nacional de Colombia. The following procedures were carried out: Amelogenin gene and short tandem repeat analyses using human identification commercial kits, conventional karyotype, SRY fluorescent in situ hybridization, PCR analysis for Y chromosome microdeletions, clinical evaluation, and genetic counseling. We present an adult male with unambiguous genitalia, karyotype 46,XX, and an SRY negative and ZFY positive molecular profile. The diagnosis of nonsyndromic 46,XX testicular disorder of sex development (DSD) -a rare genetic condition- was established. Only 20 % of similarly diagnosed patients are SRY negative and exhibit diverse molecular profiles. Until now, available evidence seems to indicate that, even in the absence of SRY, the ZFY factor is involved in male sexual differentiation.

En la mayoría de los casos, la diferenciación sexual masculina ocurre con la participación del gen SRY. Sin embargo, se pueden presentar otros genotipos excepcionales, como en el caso que se presenta en este reporte. Se trata de un paciente adulto de sexo masculino atendido en el Servicio de Paternidades del Instituto de Genética de la Universidad Nacional de Colombia. Se le hicieron los análisis del gen de la amelogenina y de repeticiones cortas en tándem (Short Tandem Repeat, STR) específicas para el gen SRY con estuches comerciales de identificación humana, así como los de cariotipo convencional e hibridación in situ fluorescente del SRY, y el estudio de microdeleciones del cromosoma Y mediante reacción en cadena de la polimerasa (PCR). Se le hizo la evaluación clínica y se le brindó asesoramiento genético. El paciente no presentaba ambigüedad genital, su cariotipo era 46 XX, y el perfil molecular era negativo para el gen SRY y positivo para el ZFY. Se le diagnosticó un trastorno de diferenciación sexual 46 XX testicular no sindrómico, una rara condición genética. Solo el 20 % de los pacientes con este diagnóstico son negativos para SRY y exhiben perfiles moleculares diversos. La información disponible parece indicar que el ZFY está relacionado con la diferenciación sexual masculina, aún en ausencia del gen SRY.

Paciente masculino con cariotipo 46 XX negativo para el gen SRY y sin ambigüedad genital: reporte de un caso / Male patient 46, XX SRY -negative and unambiguous genitalia: A case report

En la mayoría de los casos, la diferenciación sexual masculina ocurre con la participación del gen SRY. Sin embargo, se pueden presentar otros genotipos excepcionales, como en el caso que se presenta en este reporte. Se trata de un paciente adulto de sexo masculino atendido en el Servicio de Paternidades del Instituto de Genética de la Universidad Nacional de Colombia. Se le hicieron los análisis del gen de la amelogenina y de repeticiones cortas en tándem (Short Tandem Repeat, STR) específicas para el gen SRY con estuches comerciales de identificación humana, así como los de cariotipo convencional e hibridación in situ fluorescente del SRY, y el estudio de microdeleciones del cromosoma Y mediante reacción en cadena de la polimerasa (PCR). Se le hizo la evaluación clínica y se le brindó asesoramiento genético. El paciente no presentaba ambigüedad genital, su cariotipo era 46 XX, y el perfil molecular era negativo para el gen SRY y positivo para el ZFY. Se le diagnosticó un trastorno de diferenciación sexual 46 XX testicular no sindrómico, una rara condición genética. Solo el 20 % de los pacientes con este diagnóstico son negativos para SRY y exhiben perfiles moleculares diversos. La información disponible parece indicar que el ZFY está relacionado con la diferenciación sexual masculina, aún en ausencia del gen SRY.

In most cases, male sexual differentiation occurs with SRY gene mediation. However, exceptional genotypes have been identified, as shown in this paper. This was a male adult patient seen at the Servicio de Paternidades, Instituto de Genética, Universidad Nacional de Colombia. The following procedures were carried out: Amelogenin gene and short tandem repeat analyses using human identification commercial kits, conventional karyotype, SRY fluorescent in situ hybridization, PCR analysis for Y chromosome microdeletions, clinical evaluation, and genetic counseling. We present an adult male with unambiguous genitalia, karyotype 46,XX, and an SRY negative and ZFY positive molecular profile. The diagnosis of nonsyndromic 46,XX testicular disorder of sex development (DSD) -a rare genetic condition- was established. Only 20 % of similarly diagnosed patients are SRY negative and exhibit diverse molecular profiles. Until now, available evidence seems to indicate that, even in the absence of SRY, the ZFY factor is involved in male sexual differentiation.

Determinación de endogamia mediante método de isonimia en la población de Runta, Boyacá, Colombia / Determination of inbreeding by isonymy in the population of Runta, Boyacá, Colombia

Resumen Introducción. Dado el hallazgo de enfermedades raras de herencia recesiva en un número mayor de pacientes al esperado, estudios recientes han sugerido la ]presencia de un aislado poblacional en la vereda de Runta, en el departamento de Boyacá, Colombia. Esto indica la probabilidad de una tasa de consanguinidad aumentada en dicha población. Objetivos. Determinar los parámetros de endogamia mediante isonimia para analizar la estructura poblacional de la vereda Runta y ayudar a elucidar las causas de la aparición de estas enfermedades. Materiales y métodos. Se establecieron seis parámetros indicativos de estructura poblacional basados en los apellidos registrados en la base de datos del Sistema de Identificación y Selección de Potenciales Beneficiarios de Programas Sociales de los habitantes de Runta. Resultados. Se obtuvo coeficiente de endogamia (θii) de 0.0083, alfa de Fisher (α) de 30.0447 y estimativos A, B y C de 0.0379, 0.3413 y 0.4669, respectivamente. La mayoría de los individuos se encontraron agrupados en los apellidos más frecuentes de la población. Los parámetros de isonimia en Runta son similares a los de comunidades aisladas descritas en la literatura. Conclusión. Los resultados soportan la hipótesis previa de que se está ante un aislado genético en una población muy cercana a la capital del departamento de Boyacá.

Abstract Introduction: Recent studies have suggested the presence of a genetic isolate in the village of Runta, located in the department of Boyacá, Colombia, given the finding of a larger number of patients with rare diseases than expected for this population. This finding indicates the probability of an increased rate of inbreeding in this community. Objectives: To determine inbreeding parameters using isonymy to analyze the population structure of this village and to help elucidate the causes of these diseases. Materials and methods: Six parameters indicative of population structure were established based on the surnames registered in the database of the Potential Beneficiaries of Social Programs Identification and Selection System of the inhabitants of Runta. Results: Results showed an inbreeding coefficient (θii) of 0.0083, Fisher's alpha (α) of 30.0447 and A, B and C estimates of 0.0379, 0.3413 and 0.4669, respectively. Most individuals had the most popular surnames of the village, while isonymy parameters in Runta were found to be similar to those of isolated communities previously described in the literature. Conclusion: These results support the hypothesis that there is indeed a genetic isolate located near the capital of the department of Boyacá.

Determination of genotypic and clinical characteristics of Colombian patients with mucopolysaccharidosis IVA.

BACKGROUND: As mucopolysaccharidosis IVA (MPS IVA) is the most frequent MPS in Colombia, this paper aims to describe its clinical and mutational characteristics in 32 diagnosed patients included in this study. METHODS: Genotyping was completed by amplification and Sanger sequencing of the GALNS gene. The SWISS-model platform was used for bioinformatic analysis, and mutant proteins were generated by homology from the wild-type GALNS code 4FDI template from the Protein Data Bank (PDB) database. Docking was performed using the GalNAc6S ligand (PubChem CID: 193456) by AutoDock Vina 1.0 and visualized in PyMOL and LigPlot+. RESULTS: Eleven variants were identified, and one new pathogenic variant was described in the heterozygous state, which is consistent with genotype c. 319 G> T or p.Ala107Ser. The pathogenic variant c.901G>T or p.Gly301Cys was the most frequent mutation with 51.6% of alleles. Docking revealed affinity energy of -5.9 Kcal/mol between wild-type GALNS and the G6S ligand. Some changes were evidenced at the intermolecular interaction level, and affinity energy for each mutant decreased. CONCLUSION: Clinical variables and genotypic analysis were similar to those reported for other world populations. Genotypic data showed greater allelic heterogeneity than those previously reported. Bioinformatics tools showed differences in the binding interactions of mutant proteins with the G6S ligand, in regard the wild-type GALNS.

Incidentalome in Neurogenetics: Pathogenic Variant of NSD1 in a Patient With Spinocerebellar Ataxia (SCA).

Background: Genetic studies of late-onset sporadic ataxias (>40 years of age) are not routinely indicated. For unresolved cases, next-generation sequencing (NGS) tools, such as whole-exome sequencing (WES), are available for a definitive diagnosis. Case presentation: Our patient is a woman with a usual facial phenotype and anthropometry, who developed ataxia at 45 years of age, with no relevant family history and an initial clinical approach that ruled out common aetiologies. WES was performed when the patient was 54 years old. The results identified the heterozygous pathogenic variant c.248delA (p.N83MfsX4) in the nuclear receptor-binding SET domain protein 1 (NSD1; MIM 606681) gene (related to Sotos syndrome), which was not associated with ataxia and is not related to the patient's phenotype. Sanger sequencing of NSD1 in two different laboratories confirmed the variant. Conclusions: NGS findings generally offer valuable information that can be used for clinical decision-making. However, an incidental finding that leads to defining new clinical and bioethical actions is also possible. Consequently, the biological importance of this type of genetic "incidentalome" must be determined.

Novel mutation of FKBP10 in a pediatric patient with osteogenesis imperfecta type XI identified by clinical exome sequencing.

Osteogenesis imperfecta (OI) is a hereditary disease characterized by bone fragility caused by mutations in the proteins that support the formation of the extracellular matrix in the bone. The diagnosis of OI begins with clinical suspicion, from phenotypic findings at birth, low-impact fractures during childhood or family history that may lead to it. However, the variability in the semiology of the disease does not allow establishing an early diagnosis in all cases, and unfortunately, specific clinical data provided by the literature only report 28 patients with OI type XI. This information is limited and heterogeneous, and therefore, detailed information on the natural history of this disease is not yet available. This paper reports the case of a male patient who, despite undergoing multidisciplinary management, did not have a diagnosis for a long period of time, and could only be given one with the use of whole-exome sequencing. The use of the next-generation sequencing in patients with ultrarare genetic diseases, including skeletal dysplasias, should be justified when clear clinical criteria and an improvement in the quality of life of the patients and their families are intended while reducing economic and time costs. Thus, this case report corresponds to the 29th patient affected with OI type XI, and the 18th mutation in FKBP10, causative of this pathology.

Caracterización de pacientes con enfermedades genéticas del esqueleto en un centro colombiano de remisión / Characterization of patients with skeletal genetic diseases in a Colombian referral center

RESUMEN Introducción. La prevalencia de talla baja en Colombia es de 10 %, aproximadamente. En el 2009, la International Skeletal Dysplasia Society incluyó 456 condiciones clínicas en su clasificación, con base en criterios bioquímicos, radiológicos y moleculares para su diagnóstico. Objetivo. Analizar las variables demográficas, epidemiológicas y clínicas en un grupo de pacientes con enfermedades genéticas del esqueleto, remitidos al Instituto de Ortopedia Infantil Roosevelt. Materiales y métodos. Se analizaron pacientes remitidos entre el 2008 y el 2014, con 167 diagnósticos relacionados con enfermedades genéticas del esqueleto según la Clasificación Internacional de Enfermedades, versión 2010 (CIE-10). Se exploraron las variables demográficas, epidemiológicas y clínicas empleando estadística descriptiva. Se generó una puntuación para las intervenciones que contempló las combinaciones de tratamientos, y se analizaron las variables mediante la prueba t de Student. Resultados. El motivo de consulta más frecuente fue por sospecha de enfermedad genética del esqueleto. Entre los tipos de tratamiento, se consideraron los de soporte, los quirúrgicos, el farmacológico y la 'ortesis', y se pudo establecer que los pacientes con enfermedades genéticas del esqueleto obtenían puntajes mayores en la variable de intervención y menores en las de talla alta y baja. Conclusiones. El diagnóstico de la mayoría de los pacientes remitidos respondía a enfermedades genéticas del esqueleto, talla baja y otras enfermedades genéticas monogénicas. Se encontraron diferencias significativas entre la edad de inicio de los síntomas y la de diagnóstico, así como diversos enfoques terapéuticos. Hubo menos intervenciones en los pacientes con talla alta y baja, lo cual podría alertar sobre la necesidad de reevaluar las necesidades terapéuticas de este grupo.

ABSTRACT Introduction: Short height in Colombia has an estimated prevalence of 10%. The 2009 Nosology and Classification of Skeletal Genetic Diseases described 456 clinical conditions using biochemical, molecular and radiological criteria for diagnosis. Objective: To analyze demographic, epidemiological and clinical variables in a group of patients with skeletal genetic diseases referred to the Instituto de Ortopedia Infantil Roosevelt. Materials and methods: Patients referred between 2008 and 2014 were analyzed filtering 167 diagnoses of the International Classification of Diseases, 10th revision (ICD 10), related to skeletal genetic diseases. Demographic, epidemiological and clinical variables were explored using descriptive statistics. An intervention score was generated contemplating different combinations of treatments. An inferential statistical analysis using Student's t test was performed on such variables. Results: The most frequent reason for consultation was suspicion of a genetic skeletal disorder. The types of treatments considered included support, surgical, pharmacological and orthotics, and it was established that genetic skeletal disorders were associated with higher intervention scores while tall and short height showed a lower score. Conclusions: Most referred patients were classified with genetic bone diseases, short stature and other monogenic genetic diseases. Significant differences were found between the age at symptoms onset and the age of diagnosis. Diversity was found in the therapeutic approach among different groups of pathologies. Patients with tall and short height showed lower intervention scores, which may warn on the need to reassess the therapeutic requirements of these groups.

[Characterization of patients with skeletal genetic diseases in a Colombian referral center].

INTRODUCTION: Short height in Colombia has an estimated prevalence of 10%. The 2009 Nosology and Classification of Skeletal Genetic Diseases described 456 clinical conditions using biochemical, molecular and radiological criteria for diagnosis. OBJECTIVE: To analyze demographic, epidemiological and clinical variables in a group of patients with skeletal genetic diseases referred to the Instituto de Ortopedia Infantil Roosevelt. MATERIALS AND METHODS: Patients referred between 2008 and 2014 were analyzed filtering 167 diagnoses of the International Classification of Diseases, 10th revision (ICD 10), related to skeletal genetic diseases. Demographic, epidemiological and clinical variables were explored using descriptive statistics. An intervention score was generated contemplating different combinations of treatments. An inferential statistical analysis using Student's t test was performed on such variables. RESULTS: The most frequent reason for consultation was suspicion of a genetic skeletal disorder. The types of treatments considered included support, surgical, pharmacological and orthotics, and it was established that genetic skeletal disorders were associated with higher intervention scores while tall and short height showed a lower score. CONCLUSIONS: Most referred patients were classified with genetic bone diseases, short stature and other monogenic genetic diseases. Significant differences were found between the age at symptoms onset and the age of diagnosis. Diversity was found in the therapeutic approach among different groups of pathologies. Patients with tall and short height showed lower intervention scores, which may warn on the need to reassess the therapeutic requirements of these groups.

Genética clínica comunitaria: exploración de patología genética en Boyacá, Colombia / Clinical community genetics: exploring genetic disorders in Boyacá, Colombia

RESUMEN Objetivo Explorar la presencia de patología genética sindrómica en el Departamento de Boyacá, mediante un acercamiento de medicina genética comunitaria. Materiales y Métodos Un grupo conformado por genetistas, neurólogo pediátrico y genetista bioquímico, llevó a cabo jornadas clínicas en las cuales se evaluaron pacientes con sospecha de enfermedad genética. Se obtuvieron datos demográficos, epidemiológicos y clínicos y se realizó el cálculo de frecuencias de los mismos. En los centros de referencia visitados se realizaron actividades de capacitación al personal médico. Resultados Se encontraron dos agrupamientos genéticos: MPSIII y Síndrome de Ellis Van Creveld, con incidencias mayores a lo reportado en la literatura, además una alta frecuencia de patologías de herencia autosómica recesiva, así como sospecha de síndromes de microdeleción-microduplicación. Conclusiones Se deben establecer mecanismos no convencionales de atención médica para facilitar el acceso a las comunidades a un diagnóstico y tratamiento adecuados en genética. Se espera que el apoyo brindado a los pacientes, familias y personal asistencial de los hospitales a través de las jornadas clínicas y la capacitación, permitan alcanzar este objetivo y a la vez sea un punto de inicio de procesos de prevención primaria y secundaria.(AU)

ABSTRACT Objectives To explore the incidence of syndromic genetic pathologies in Boyacá, Colombia, through a community genetics approach. Materials and Methods A group made up by different medical specialists (geneticists, a pediatric neurologist, and a biochemical geneticist) developed clinical campaigns, in which patients with clinical suspicion of genetic diseases were involved. Demographic, epidemiological and clinical data were collected, and frequency calculations were made based on the collected data. Several training workshops for health personnel were done in each center visited. Results Two genetic clusters were found: mucopolysaccharidosis type III, and Ellis-Van Creveld Syndrome, both of them with higher incidences than those found in the literature. Also, a high frequency of autosomal recessive diseases was found, as well as microdeletion/microduplication syndromes. Conclusions Conventional mechanisms of medical attention must be established, in order to facilitate the access to an appropriate diagnosis and treatment. This work intended to provide support to patients, families and health care services personnel through the workshops and clinical campaigns, and to become a starting point to develop primary and secondary prevention processes.(AU)

[Clinical community genetics: exploring genetic disorders in Boyacá, Colombia]. / Genética clínica comunitaria: exploración de patología genética en Boyacá, Colombia.

OBJECTIVES: To explore the incidence of syndromic genetic pathologies in Boyacá, Colombia, through a community genetics approach. MATERIALS AND METHODS: A group made up by different medical specialists (geneticists, a pediatric neurologist, and a biochemical geneticist) developed clinical campaigns, in which patients with clinical suspicion of genetic diseases were involved. Demographic, epidemiological and clinical data were collected, and frequency calculations were made based on the collected data. Several training workshops for health personnel were done in each center visited. RESULTS: Two genetic clusters were found: mucopolysaccharidosis type III, and Ellis-Van Creveld Syndrome, both of them with higher incidences than those found in the literature. Also, a high frequency of autosomal recessive diseases was found, as well as microdeletion/microduplication syndromes. CONCLUSIONS: Conventional mechanisms of medical attention must be established, in order to facilitate the access to an appropriate diagnosis and treatment. This work intended to provide support to patients, families and health care services personnel through the workshops and clinical campaigns, and to become a starting point to develop primary and secondary prevention processes.

OBJETIVO: Explorar la presencia de patología genética sindrómica en el Departamento de Boyacá, mediante un acercamiento de medicina genética comunitaria. MATERIALES Y MÉTODOS: Un grupo conformado por genetistas, neurólogo pediátrico y genetista bioquímico, llevó a cabo jornadas clínicas en las cuales se evaluaron pacientes con sospecha de enfermedad genética. Se obtuvieron datos demográficos, epidemiológicos y clínicos y se realizó el cálculo de frecuencias de los mismos. En los centros de referencia visitados se realizaron actividades de capacitación al personal médico. RESULTADOS: Se encontraron dos agrupamientos genéticos: MPSIII y Síndrome de Ellis Van Creveld, con incidencias mayores a lo reportado en la literatura, además una alta frecuencia de patologías de herencia autosómica recesiva, así como sospecha de síndromes de microdeleción-microduplicación. CONCLUSIONES: Se deben establecer mecanismos no convencionales de atención médica para facilitar el acceso a las comunidades a un diagnóstico y tratamiento adecuados en genética. Se espera que el apoyo brindado a los pacientes, familias y personal asistencial de los hospitales a través de las jornadas clínicas y la capacitación, permitan alcanzar este objetivo y a la vez sea un punto de inicio de procesos de prevención primaria y secundaria.

Natural History of Sanfilippo Syndrome Type C in Boyacá, Colombia.

Mucopolysaccharidosis type III, or Sanfilippo syndrome, is an autosomal recessive disorder characterized by impairment in the degradation of Heparan sulfate. Here the authors describe the natural history of 5 related individuals; all associated through a large pedigree which reports a total of 11 affected members, originally from the Boyacá region in Colombia, diagnosed with MPS IIIC who all harbor a novel mutation in HGSNAT. The authors report an unusually high incidence of the disease in this population. The clinical features are similar to previously described patients, although some differences in the degree of severity and end-stage of the disease are seen in this specific group. The authors consider that the high degree of endogamy in this specific population could underlie modifying factors for the severity of presentation in these patients. Future studies might provide more information on the functional effect of this novel mutation, which could define this group as a genetic isolate.

Charcot Marie Tooth disease (CMT4A) due to GDAP1 mutation: report of a colombian family / Enfermedad de Charcot Marie Tooth (CMT4A) por mutacion en el gen GDAP1: reporte de una familia colombiana

Background: Mutations of GDAP1 gene cause autosomal dominant and autosomal recessive Charcot-Marie-Tooth disease and more than 40 different mutations have been reported. The recessive Q163X mutation has been described in patients of Spanish ancestry, and a founder mutation in South American patients, originating in Spain has been demonstrated. Objective: We describe physical and histological features, and the molecular impact of mutation Q163X in a Colombian family. Methods: We report two female patients, daughters of consanguineous parents, with onset of symptoms within the first two years of life, developing severe functional impairment, without evidence of dysmorphic features, hoarseness or diaphragmatic paralysis. Electrophysiology tests showed a sensory and motor neuropathy with axonal pattern. Sequencing of GDAP1 gene was requested and the study identified a homozygous point mutation (c.487 C>T) in exon 4, resulting in a premature stop codon (p.Q163X). This result confirms the diagnosis of Charcot-Marie-Tooth disease, type 4A. Results: The patients were referred to Physical Medicine and Rehabilitation service, in order to be evaluated for ambulation assistance. They have been followed by Pulmonology service, for pulmonary function assessment and diaphragmatic paralysis evaluation. Genetic counseling was offered. The study of the genealogy of the patient, phenotypic features, and electrophysiological findings must be included as valuable tools in the clinical approach of the patient with Charcot-Marie-Tooth disease, in order to define a causative mutation. In patients of South American origin, the presence of GDAP1 gene mutations should be considered, especially the Q163X mutation, as the cause of CMT4A disease.

Antecedentes: Las mutaciones del gen GDAP1 son causantes de la enfermedad de Charcot Marie Tooth tanto autosómica dominante como recesiva, y se han reportado más de 40 mutaciones distintas. La mutación recesiva Q163X ha sido descrita en pacientes de ascendencia española y se ha demostrado una mutación fundadora originaria de España en pacientes de origen suramericano. Describimos las características físicas e histológicas y el impacto molecular de la mutación Q163X en una familia colombiana. Objetivo: Se describe el impacto de la mutación Q163X en las características físicas, histológicas y moleculares en una familia colombiana. Métodos: Se describe dos pacientes de sexo femenino, hijas de padres consanguíneos, quienes presentaron inicio de síntomas en los dos primeros años de vida, mostrando deterioro funcional severo, sin evidencia de dismorfía, disfonía o parálisis diafragmática. Los estudios de electrofisiología mostraron una neuropatía sensitiva y motora con patrón axonal. Se solicitó la secuenciación del gen GDAP1, y el estudio identificó una mutación homocigota puntual (c. 487 C>T) en el exón 4, causando un codón de parada prematuro (p. Q163X). Este resultado confirma el diagnóstico de Enfermedad de Charcot Marie Tooth, tipo 4A (recesiva, tipo axonal). Resultados: Las pacientes fueron remitidas al servicio de Fisiatría para evaluación de métodos de asistencia para deambulación. Ellas reciben seguimiento por el servicio de Neumología, quienes vigilan la función pulmonar y el desarrollo de parálisis diafragmática. Se brindó asesoramiento genético. La genealogía del paciente, las características fenotípicas y los hallazgos en los estudios electrofisiológicos son herramientas valiosas en el enfoque clínico del paciente con CMT, de forma que se pueda plantear una posible mutación causal. Se debe considerar la presencia de mutaciones en el gen GDAP1 en pacientes de origen suramericano, en especial la mutación Q163X, como causa de CMT4A.

Deep Genotyping of the IDS Gene in Colombian Patients with Hunter Syndrome.

BACKGROUND: Mucopolysaccharidosis type II (MPSII), also known as Hunter syndrome, is an X-linked disorder caused by mutations in the iduronate 2 sulfatase (IDS) gene. This enzyme catalyzes the initial step in the catabolism of heparan sulfate and dermatan sulfate; thus, its deficiency leads to the accumulation of these glycosaminoglycans. MPS II has significant allelic heterogeneity, making the establishment of genotype-phenotype correlations difficult. This study assessed clinical features in combination with deep genotyping of a group of Colombian patients with MPS II and attempted to establish a degree of genotype-phenotype correlation by employing bioinformatic tools. METHODS: Eighteen patients were included in this study, 11% of whom were non-neuronopathic, and the other 89% were neuronopathic. Samples were all analyzed using three molecular methodologies: MLPA, direct exon sequencing, and RFLP analysis. RESULTS: A total of 13 mutations were identified, 6 of which were novel (c.548_564dup16, c.477insT, c.595_607del12, c. 549_562del13, c.182delC, and a complete deletion of exon 7). The frequency of common mutations (R468Q, Q465X, K347Q, K236N, S71N, R88H, and a conversion phenomenon) was 53.85%. The S71N mutation was frequent among the attenuated phenotype, while private frameshift mutations and rearrangements were seen in patients with severe phenotypes. Molecular docking was performed on the wild-type and mutant IDS proteins, which revealed changes in the enzyme-substrate interaction for the mutant IDS. CONCLUSION: The frequency of novel mutations (46.15%) is similar to what has been reported elsewhere. The use of bioinformatic tools showed differences in enzyme-substrate interactions. Studies with larger groups of patients are needed.

Charcot Marie Tooth disease (CMT4A) due to GDAP1 mutation: report of a Colombian family.

BACKGROUND: Mutations of GDAP1 gene cause autosomal dominant and autosomal recessive Charcot-Marie-Tooth disease and more than 40 different mutations have been reported. The recessive Q163X mutation has been described in patients of Spanish ancestry, and a founder mutation in South American patients, originating in Spain has been demonstrated. OBJECTIVE: We describe physical and histological features, and the molecular impact of mutation Q163X in a Colombian family. METHODS: We report two female patients, daughters of consanguineous parents, with onset of symptoms within the first two years of life, developing severe functional impairment, without evidence of dysmorphic features, hoarseness or diaphragmatic paralysis. Electrophysiology tests showed a sensory and motor neuropathy with axonal pattern. Sequencing of GDAP1 gene was requested and the study identified a homozygous point mutation (c.487 C>T) in exon 4, resulting in a premature stop codon (p.Q163X). This result confirms the diagnosis of Charcot-Marie-Tooth disease, type 4A. RESULTS: The patients were referred to Physical Medicine and Rehabilitation service, in order to be evaluated for ambulation assistance. They have been followed by Pulmonology service, for pulmonary function assessment and diaphragmatic paralysis evaluation. Genetic counseling was offered. The study of the genealogy of the patient, phenotypic features, and electrophysiological findings must be included as valuable tools in the clinical approach of the patient with Charcot-Marie-Tooth disease, in order to define a causative mutation. In patients of South American origin, the presence of GDAP1 gene mutations should be considered, especially the Q163X mutation, as the cause of CMT4A disease.

ANTECEDENTES: Las mutaciones del gen GDAP1 son causantes de la enfermedad de Charcot Marie Tooth tanto autosómica dominante como recesiva, y se han reportado más de 40 mutaciones distintas. La mutación recesiva Q163X ha sido descrita en pacientes de ascendencia española y se ha demostrado una mutación fundadora originaria de España en pacientes de origen suramericano. Describimos las características físicas e histológicas y el impacto molecular de la mutación Q163X en una familia colombiana. OBJETIVO: Se describe el impacto de la mutación Q163X en las características físicas, histológicas y moleculares en una familia colombiana. MÉTODOS: Se describe dos pacientes de sexo femenino, hijas de padres consanguíneos, quienes presentaron inicio de síntomas en los dos primeros años de vida, mostrando deterioro funcional severo, sin evidencia de dismorfía, disfonía o parálisis diafragmática. Los estudios de electrofisiología mostraron una neuropatía sensitiva y motora con patrón axonal. Se solicitó la secuenciación del gen GDAP1, y el estudio identificó una mutación homocigota puntual (c. 487 C>T) en el exón 4, causando un codón de parada prematuro (p. Q163X). Este resultado confirma el diagnóstico de Enfermedad de Charcot Marie Tooth, tipo 4A (recesiva, tipo axonal). RESULTADOS: Las pacientes fueron remitidas al servicio de Fisiatría para evaluación de métodos de asistencia para deambulación. Ellas reciben seguimiento por el servicio de Neumología, quienes vigilan la función pulmonar y el desarrollo de parálisis diafragmática. Se brindó asesoramiento genético. La genealogía del paciente, las características fenotípicas y los hallazgos en los estudios electrofisiológicos son herramientas valiosas en el enfoque clínico del paciente con CMT, de forma que se pueda plantear una posible mutación causal. Se debe considerar la presencia de mutaciones en el gen GDAP1 en pacientes de origen suramericano, en especial la mutación Q163X, como causa de CMT4A.

SHOX gene and conserved noncoding element deletions/duplications in Colombian patients with idiopathic short stature.

SHOX gene mutations or haploinsufficiency cause a wide range of phenotypes such as Leri Weill dyschondrosteosis (LWD), Turner syndrome, and disproportionate short stature (DSS). However, this gene has also been found to be mutated in cases of idiopathic short stature (ISS) with a 3-15% frequency. In this study, the multiplex ligation-dependent probe amplification (MLPA) technique was employed to determine the frequency of SHOX gene mutations and their conserved noncoding elements (CNE) in Colombian patients with ISS. Patients were referred from different centers around the county. From a sample of 62 patients, 8.1% deletions and insertions in the intragenic regions and in the CNE were found. This result is similar to others published in other countries. Moreover, an isolated case of CNE 9 duplication and a new intron 6b deletion in another patient, associated with ISS, are described. This is one of the first studies of a Latin American population in which deletions/duplications of the SHOX gene and its CNE are examined in patients with ISS.

Multiplex ligation-dependent probe amplification to subtelomeric rearrangements in idiopathic intellectual disability in Colombia.

BACKGROUND: A cause cannot be determined in 30% to 50% of patients with intellectual disability. Determining the etiology of intellectual disability is important and useful for pediatric neurologists, geneticists, pediatricians, and patients' families because it allows assessment of recurrence risk, appropriate genetic counseling, and focus on treatment options and prognosis. This study aims to determine the prevalence, origin, and characterization of subtelomeric rearrangements through the Multiplex Ligation-Dependent Probe Amplification method in pediatric patients with idiopathic intellectual disability. METHODS: A cross-sectional descriptive study was undertaken with patients seen in consultation at the neuropediatrics or genetic service of the Central Military Hospital, the Mercy' Hospital, or the Genetics Institute National University of Colombia. Patients were diagnosed with idiopathic intellectual disability between December 2010 and September 2011 and underwent a complete medical history, physical examination, and assessment to rule out other etiologies of intellectual disability. Then we applied the genetic test of Multiplex Ligation-Dependent Probe Amplification to each patient's sample of peripheral blood to determine subtelomeric rearrangements. RESULTS: We studied a group of 119 patients with idiopathic intellectual disability; Multiplex Ligation-Dependent Probe Amplification showed subtelomeric rearrangements in five. In the group with subtelomeric rearrangements, the most frequent results were de novo rearrangements (80%), deletion type (60%), moderate and severe intellectual disability (80%), minor phenotypic abnormalities (80%), and family history of neurological disorders (80%). No dependence relationship was observed between subtelomeric rearrangements and family history of neurological disorders, family history of intellectual disability, severity of intellectual disability, phenotypic abnormalities, and consanguinity. CONCLUSIONS: This study determined a prevalence of subtelomeric rearrangements of 4.2% in a group of Colombian pediatric patients with idiopathic intellectual disability using the genetic test Multiplex Ligation-Dependent Probe Amplification.

Genotypic and bioinformatic evaluation of the alpha-l-iduronidase gene and protein in patients with mucopolysaccharidosis type I from Colombia, Ecuador and Peru.

Mucopolysaccharidosis type I (MPSI) is a rare autosomal recessive disorder caused by mutations in the gene encoding the lysosomal enzyme α-l-iduronidase (IDUA), which is instrumental in the hydrolysis of the glycosaminoglycans, dermatan and heparan sulfate. The accumulation of unhydrolyzed glycosaminoglycans leads to pathogenesis in multiple tissue types, especially those of skeletal, nervous, respiratory, cardiovascular, and gastrointestinal origin. Although molecular diagnostic tools for MPSI have been available since the identification and characterization of the IDUA gene in 1992, Colombia, Ecuador, and Peru have lacked such methodologies. Therefore, the mutational profile of the IDUA gene in these countries has largely been unknown. The goal of this study was to characterize genotypes in 14 patients with MPSI from Colombia, Ecuador, and Peru. The most common mutation found at a frequency of 42.8% was W402X. Six patients presented with seven novel mutations, a high novel mutational rate in this population (32%). These novel mutations were validated using bioinformatic techniques. A model of the IDUA protein resulting from three of the novel missense mutations (Y625C, P385L, R621L) revealed that these mutations alter accessible surface area values, thereby reducing the accessibility of the enzyme to its substrates. This is the first characterization of the mutational profile of the IDUA gene in patients with MPSI in Colombia, Ecuador, and Peru. The findings contribute to our understanding of IDUA gene expression and IDUA enzyme function, and may help facilitate early and improved diagnosis and management for patients with MPSI.

Report of a novel mutation in the SLC26A2 gene found in a Colombian adult patient with diastrophic dysplasia / Reporte de una nueva mutación en el gen SLC26A2 en un paciente adulto colombiano con displasia diastrófica

Summary Background. Diastrophic dysplasia is an osteochondrodysplasia belonging to the group of dysplasias caused by mutations in the diastrophic dysplasia sulfate transporter. This sindrome is a micromelic dysplasia with multiple bone deformities of the hands, feet, knees and spine. Objective. Describe the first report of diastrophic displasia in Colombia Materials and methods. In this paper a Colombian adult patient with diastrophic dysplasia whose clinical diagnosis was confirmed at the molecular level is reported. Results. In this first report of diastrophic dysplasia in Colombia we found that the patient was compound heterozygote for the already reported Arg279Trp substitution and an unpublished mutation, a Ser157Thr substitution in the SLC26A2 gene. Conclusion. Bioinformatic analysis on the latter mutation suggested that it could correspond to a deleterious mutation because it is in a highly conserved domain of the sulfate transporter.

Resumen Antecedentes. La displasia diastrófica es una osteocondrodisplasia que pertenece al grupo de las enfermedades genéticas del esqueleto causadas por mutaciones en los transportadores de sulfato. Se presenta como una displasia micromélica con afectación de múltiples huesos y deformidades en manos, pies, rodillas y columna vertebral. Objetivo. Describir el primer reporte de displasia diastrófica en Colombia. Materiales y métodos. Se reporta un adulto colombiano con esta displasia, con confirmación clínica, radiológica y molecular. Resultados. En este primer reporte colombiano, se encontró que la paciente presentó una mutación heterocigota compuesta, de Arg279Trp y Ser157Thr, esta última no reportada previamente, en el gen SLC26A2. Conclusión. El análisis bioinformático de la mutación nueva sugiere que podría corresponder a una mutación deletérea dado que el dominio afectado en el transportador de sulfatos es altamente conservado.