Clinical, imaging, and molecular findings in a sample of Mexican families with pantothenate kinase-associated neurodegeneration.

Pantothenate kinase-associated neurodegeneration (PKAN) is an autosomal recessive disorder characterized by iron accumulation in the brain, because of mutations in the PANK2 gene. Phenotypic and genotypic characteristics of 11 patients from five Mexican families with PKAN disease are reported. Sequencing of PANK2 confirmed the diagnosis. The 11 patients had dysarthria associated with dystonia and Parkinsonism in six. Brain magnetic resonance imaging (MRI) showed the 'eye-of-the-tiger' sign in all patients. Three different mutations were identified, a novel one (p.A469P) and two (p.G219V and p.N404I) very rare. Homozygous sibs for the p.G219V mutation had a severe disease progression with early death. Dystonia predominated in the p.A469P/p.N404I compound heterozygous patients. Homozygous for p.N404I showed Parkinsonism, tics and personality and speech disorders. Early and late disease onset and variable expression was present in carriers of the different identified mutations. The 'eye-of-the-tiger' is an excellent neuroimaging hallmark to predict PANK2 mutations. We detected a 'cluster' of patients harboring the p.N404I mutation, strongly suggesting a founder effect for this mutation. This is the first familial clinical-genetic PKAN disease study accomplished in Mexico.

Macular optical coherence tomography findings and GPR143 mutations in patients with ocular albinism.

The aim of this study was to describe macular findings using spectral-domain optical coherence tomography (SD-OCT) in patients with ocular albinism (OA) and their carrier mothers, and to identify the frequency of GPR143 gene mutations in these patients. The study included five patients with a clinical diagnosis of OA. SD-OCT of the macular area was performed in both patients and their mothers. The anatomical characteristics of the macula and retinal pigment epithelium (RPE), patterns of autofluorescence and infrared imaging were analyzed. Polymerase chain reaction amplification of the complete coding sequence of GPR 143 was performed and subsequently analyzed by direct sequencing in patients and their possible carrier mothers. SD-OCT images revealed the presence of inner retinal layers in the fovea, an abnormal disposition of the Henle layer and a lack of thickening in the perifoveal area. We found increased thickness in the RPE to the outer segment and in the outer segment to the outer nuclear layer that is associated with increased visual acuity. Autofluorescence images revealed an absence of normal hipoautofluorescence in the fovea. No changes were observed in the images of their carrier mothers. Mutation screening and sequence analysis of the GPR 143 gene revealed a novel pathological mutation in two patients. Abnormalities in the macula were observed in all patients. SD-OCT is a useful tool for the assessment of patients with OA. No changes were observed in the SD-OCT of carrier mothers. Only two patients had the GPR143 gene mutation.

High TGM1 Allelic Heterogeneity causing Lamellar ichthyosis in a small geographic area in South Mexico: Another Example of the "Réunion Paradox".

Lamellar ichthyosis (LI) is an autosomal recessive congenital ichthyosis characterized by generalized dry skin and severe scaling. It is caused by biallelic mutations in the TGM1 gene, however molecular data from non-Caucasian populations are limited. Results of genetic-molecular analysis of a group of LI pedigrees originating from two close small populations from south Mexico are presented. LI affected individuals belonging to 9 apparently unrelated families were studied. Exome sequencing or Sanger sequencing in probands from each family was carried out. Furthermore, DNA from 294 unaffected subjects from one of the communities were Sanger sequenced to determine the carrier frequency of the c.427C > T TGM1 variant. Five different TGM1 pathogenic variants, either in homozygous or in compound heterozygous state, were demonstrated in affected subjects. The two most common variants were c.427C > T (p.Arg143Cys) and c.1159+1G > T. A novel c.1645+1G > T TGM1 pathogenic allele was recognized. Carrier frequency analysis identified a total of 23 individuals heterozygous for the c.427C > T variant, predicting a prevalence of 78 carriers per 1000 inhabitants in the community. A high TGM1 allelic heterogeneity with 5 different LI-causing alleles in a limited geographic area was demonstrated. While the occurrence of homozygosity for a founder mutation is expected in small populations with high frequency of a particular autosomal recessive disorder, the occurrence of multiple pathogenic alleles has been previously described, a situation known as the Reúnion paradox. Our results expand the current knowledge of the mutational spectrum of TGM1-linked LI.

Case report: Disease phenotype associated with simultaneous biallelic mutations in ABCA4 and USH2A due to uniparental disomy of chromosome 1.

Inherited retinal diseases (IRDs) represent a spectrum of clinically and genetically heterogeneous disorders. Our study describes an IRD patient carrying ABCA4 and USH2A pathogenic biallelic mutations as a result of paternal uniparental disomy (UPD) in chromosome 1. The proband is a 9-year-old girl born from non-consanguineous parents. Both parents were asymptomatic and denied family history of ocular disease. Clinical history and ophthalmologic examination of the proband were consistent with Stargardt disease. Whispered voice testing disclosed moderate hearing loss. Next-generation sequencing and Sanger sequencing identified pathogenic variants in ABCA4 (c.4926C>G and c.5044_5058del) and USH2A (c.2276G>T). All variants were present homozygously in DNA from the proband and heterozygously in DNA from the father. No variants were found in maternal DNA. Further analysis of single nucleotide polymorphisms confirmed paternal UPD of chromosome 1. This is the first known patient with confirmed UPD for two recessively mutated IRD genes. Our study expands on the genetic heterogeneity of IRDs and highlights the importance of UPD as a mechanism of autosomal recessive disease in non-consanguineous parents. Moreover, a long-term follow-up is essential for the identification of retinal features that may develop as a result of USH2A-related conditions.

Immunophenotyping in peripheral blood mononuclear cells, aqueous humour and vitreous in a Blau syndrome patient caused by a novel NOD2 mutation.

The genetic and immunophenotypic characteristics of a 3-year-old patient with Blau syndrome (BS), an early onset sarcoidosis caused by mutations in NOD2, were investigated. Molecular analysis of NOD2 gene was achieved by PCR and direct nucleotide sequencing. Immunophenotyping included cytometric analysis of memory-effector markers on T-cells, and cytokine in serum, aqueous humour and vitreous. A novel M513R mutation in NOD2 was demonstrated. Immunophenotyping revealed higher frequency of CCR4+ cells and CCR9+ cells on CD4+ cells; most CD8+ cells were CCR7- and CCR9+. IL6 and IL-8 were detected in a gradient manner: vitreous humour>aqueous humour>serum. The immunophenotype in this patient was characterized by a differential expression of chemokine receptors on T cells and by a particular ocular microenvironment enriched in IL-6 and IL-8. To our knowledge, this is the first study analysing the immunological features of BS at aqueous humour, vitreous and blood levels. Our results expand the knowledge of the genetic and immunopathological basis of BS.

Mutations in rpoB and katG genes in Mycobacterium isolates from the Southeast of Mexico.

The most frequent mutations associated with rifampin and isoniazid resistance in Mycobacterium are the substitutions at codons 531 and 315 in the rpoB and katG genes, respectively. Hence, the aim of this study was to characterize these mutations in Mycobacterium isolates from patients suspected to be infected with drug-resistant (DR) pulmonary tuberculosis (TB) in Veracruz, Mexico. Drug susceptibility testing of 25 clinical isolates revealed that five were susceptible while 20 (80%) were DR (15% of the annual prevalence for Veracruz). Of the DR isolates, 15 (75%) were resistant to rifampin, 17 (85%) to isoniazid and 15 (75%) were resistant to both drugs (MDR). Sequencing analysis performed in the isolates showed that 14 (93%) had mutations in the rpoB gene; seven of these (47%) exhibited a mutation at 531 (S-->L). Ten (58%) of the 20 resistant isolates showed mutations in katG; nine (52%) of these 10 exhibited a mutation at 315 (S-->T). In conclusion, the DR profile of the isolates suggests a significant number of different DR-TB strains with a low frequency of mutation at codons 531 and 315 in rpoB and katG, respectively. This result leads us to consider different regions of the same genes, as well as other genes for further analysis, which is important if a genetic-based diagnosis of DR-TB is to be developed for this region.

[PCR-based detection of heteroplasmic deleted mitochondrial DNA in Kearns-Sayre syndrome]. / Detección de deleciones en DNA mitocondrial heteroplásmico por medio de PCR EN el síndrome de Kearns-Sayre.

OBJECTIVE: To describe the clinical data and the results of molecular analyses of the mitochondrial DNA in a patient with Kearns-Sayre Syndrome. METHODS: Molecular analyses of mitochondrial DNA from the patient included PCR amplification of a region where the common Kearns- Sayre deletion is located and Genotype-Phenotype correlations are discussed. RESULTS: The affected patient showed ptosis, progressive external ophthalmoplegia, pigmentary changes in the peripheral retina and right bundle block. Molecular analysis disclosed a approximately 5 kb deletion in the mitochondrial DNA and some wild type mtDNA indicating heteroplasmy. CONCLUSIONS: Molecular analysis of mitochondrial DNA confirmed the clinical diagnosis of Kearns-Sayre syndrome. PCR provides a rapid method to identify the common 4997 bp deletion in Kearns-Sayre syndrome. In such cases, PCR diagnosis could avoid invasive methods such as muscle biopsy or spinal tap.

Familial exudative vitreoretinopathy: A report of an asymptomatic case with autosomal dominant inheritance detected using FZD4 molecular analysis. / Vitreorretinopatía exudativa familiar, reporte de un caso asintomático con herencia autosómica dominante, detectado mediante análisis molecular de FZD4.

OBJECTIVE: To report a familial case of Familial Exudative Vitreoretinopathy (FEVR) with an autosomal dominant inheritance pattern identified with the molecular analysis of FZD4. CASE REPORT: The proband is a 13 year-old boy who consulted for low vision. Fundus examination revealed a peripheral avascular zone and macular dragging, consistent with FEVR. Molecular analysis demonstrated a mutation of FZD4 in DNA from both the patient and his asymptomatic mother. DISCUSSION: This familial case was identified with the molecular analysis of FZD4 and shows the importance to explore first degree relatives in a sporadic FEVR case.

[Autosomal dominant granular corneal dystrophy caused by a TGFBI gene mutation in a Mexican family]. / Distrofia corneal granular autosómica dominante causada por mutación del gen TGFBI en una familia Mexicana.

OBJECTIVE: To describe the clinical data and the results of molecular analyses of the TGFBI gene in a patient with classic granular stromal corneal dystrophy (type I). METHODS: A female patient aged 60-years complaining of a long-standing decrease of visual acuity bilaterally associated with photophobia and foreign body sensation, underwent a complete ophthalmologic examination. Molecular analyses of DNA from the patient and from an affected brother included PCR amplification of exons 4, 11, 12, and 14 of the TGFBI gene and direct automated sequencing of the PCR products. RESULTS: The affected patient showed a pattern of corneal stromal lesions that was compatible with a diagnosis of classic granular dystrophy. No involvement of other corneal layers was evident. Molecular analysis disclosed a point mutation in exon 14 of the TGFBI gene which consisted of an adenine to guanine change at nucleotide position 1924, predicting a substitution of arginine instead of histidine at residue 626 of the TGFBI protein (H626R). An identical mutation was detected in DNA from her affected brother. CONCLUSIONS: This is the first time that a case of stromal granular dystrophy has been demonstrated to be caused by the H626R mutation, a molecular defect classically detected in the phenotypically distinct lattice corneal dystrophy. Our data indicate that the same molecular defects in the TGFBI gene lead to different phenotypes in stromal dystrophies, thus expanding the genotypic-phenotypic spectrum in this group of corneal diseases.

Clinical and cytogenetic findings in 14 patients with madelung anomaly.

Madelung deformity of the wrist is a congenital defect caused by a growth disturbance in the volar-ulnar distal radial physis leading to a typical appearance of the upper extremities. The majority of Madelung deformity case caused by hereditary dyschondrosteosis of the wrist. In a number of instances, the disease has a genetic etiology. This article reports the clinical and cytogenetic findings associated with Madelung deformity in 14 patients. Results indicate Madelung anomaly often is associated with additional clinical abnormalities, particularly delayed puberty and menstrual disorders, as well as sexual chromosome aberrations.

Evidence for genetic heterogeneity in male pseudohermaphroditism due to Leydig cell hypoplasia.

Leydig cell aplasia or hypoplasia is a rare form of male pseudohermaphroditism resulting from inadequate fetal testicular Leydig cell differentiation. Affected individuals presented a wide phenotypic spectrum, ranging from complete female external genitalia to males with micropenis. Recessive mutations in the LH receptor gene have been identified as responsible for the condition. The majority of these mutations are point mutations and have been located in exon 11 of the gene. In this study, we report the molecular characterization of the LH receptor gene in three siblings with Leydig cell hypoplasia. After sequencing the 11 exons of the gene, no deleterious mutations were detected in any patient. However, we identified a previously described polymorphism in exon 11. In patients 1 and 3 DNA sequencing revealed a C to T substitution at nucleotide 1065; both patients were homozygous GAT/GAT at codon 355. In contrast, patient 2 was homozygous GAC/GAC, whereas the father and one unaffected sister were heterozygous GAC/GAT at this polymorphic site. These results exclude that Leydig cell hypoplasia in this family is due to a mutation in the LH receptor gene and provide evidence that defects in other loci may also result in failure of Leydig cell differentiation, demonstrating, for the first time, that Leydig cell hypoplasia is a genetically heterogeneous condition.

A recurrent missense mutation in the KAL gene in patients with X-linked Kallmann's syndrome.

Kallmann's syndrome (KS) is defined by the association of hypogonadotropic hypogonadism and anosmia or hyposmia. Segregation analysis in familial cases has demonstrated diverse inheritance patterns, suggesting the existence of several genes regulating GnRH secretion. Genetic defects have been demonstrated in the KAL gene, located on the Xp22.3 region, explaining the X-linked form of the disease. We report molecular findings regarding the KAL gene in 12 unrelated males with X-linked KS. PCR of the 14 exons of the KAL gene was performed on genomic DNA. PCR products of all exons were purified and sequenced. Genetic defects in the KAL gene were found in 7 patients. One exhibits a deletion from exon 3 to exon 5. Six individuals present a previously unidentified missense mutation in exon 11, consisting of a G to A substitution at codon 514 (GAA to AAA). In the remaining 5 individuals, no mutations were observed. We also found three different polymorphic changes. The first one, in exon 2, had not been reported previously. The other two were located at exons 11 and 12. The deletion described, comprises only part (exon 5) of the coding region of the first fibronectin type III-like repeat of the KAL protein. The rest of the deletion comprises part of the conserved cysteine-rich N-terminal region that corresponds to the whey acidic protein motif. The same missense mutation was found in 6 of the 12 patients, indicating the possibility that it derived from a common ancestor or suggesting the presence of a hot spot in this region of the gene.

Clinical expression and SRY gene analysis in XY subjects lacking gonadal tissue.

In several syndromes genetic males lack gonadal tissue. A range of phenotypes are seen, which varies from complete female external genitalia to anorchic subjects with sexual infantilism. Differences in phenotypic expression depend on the stage at which testes degenerated during intrauterine development. Although most cases of these syndromes are sporadic, several instances of familial recurrence suggest a genetic origin. To help elucidate the source, we performed molecular analysis of the complete SRY gene open reading frame in two subjects with true agonadism and in two with anorchia. Our results add to previous findings indicating that molecular defects in SRY are not readily identified as a cause of these syndromes.

Partially deleted SRY gene confined to testicular tissue in a 46,XX true hermaphrodite without SRY in leukocytic DNA.

True hermaphroditism is an uncommon form of intersexuality in which testicular and ovarian tissue develop in the same individual. Most true hermaphrodites are 46,XX and lack SRY, the testis-determining gene. We describe results of molecular studies performed in a 46,XX true hermaphrodite SRY-negative in DNA from blood leukocytes but SRY-positive in DNA obtained from the testicular portion of the ovotestis. Surprisingly, the SRY identified in gonadal DNA carries a partial deletion at the 5' end of the gene. Our patient is the first case of a naturally occurring deletion within the SRY ORF (with a normal HMG box) and provides a new explanation for the abnormal gonadal development observed in 46,XX true hermaphrodites.

Mutational analysis of HOXD13 and HOXA13 genes in the triphalangeal thumb-brachyectrodactyly syndrome.

The triphalangeal thumb-brachyectrodactyly syndrome is a very rare autosomal dominant disorder of unknown etiology characterized by an unusual pattern of limb malformations: triphalangeal thumbs and brachyectrodactyly in the hands, and ectrodactyly in the feet. In a previous report, we described the clinical and radiographical features of three related subjects with the disease and suggest that due to the unusual combination of limb defects and to its phenotypic similarity with the limb malformative pattern induced by disrupting the Hoxd13 gene in mouse, the triphalangeal thumb-brachyectrodactyly syndrome might be caused by mutations in a HOX gene. After sequencing the entire coding region of HOXD13 and the highly conserved homeodomain encoding region of HOXA13, we do not detect any deleterious mutation in any of the patients excluding that alterations at these sequences are responsible for the disease. Mutations in regulatory regions of these genes or in other genes involved in limb development might be responsible for the disease.

p63 gene analysis in Mexican patients with syndromic and non-syndromic ectrodactyly.

Ectrodactyly is a congenital limb malformation that involves a central reduction defect of the hands and/or feet which is frequently associated with other phenotypic abnormalities. The condition appears to be genetically heterogeneous and recently it has been demonstrated that mutations in the p63 gene, a homologue of the tumor suppressor gene p53, are the cause of at least four autosomal dominant genetic syndromes which feature ectrodactyly: ectrodactyly, ectodermal dysplasia, and facial clefting (EEC), split hand/split foot malformation (SHFM), limb-mammary syndrome (LMS), and acro-dermato-ungual-lacrimal-tooth syndrome (ADULT). In this study, genetic analysis of the p63 gene in a group of 13 patients with ectrodactyly (syndromic and isolated) was performed. Four patients with syndromic ectrodactyly had p63 heterozygous point mutations that affect the DNA binding domain of the protein. One of these subjects exhibited the typical features of EEC syndrome as well as ankyloblepharon being, to our knowledge, the first case combining these traits. This finding supports the view of a clinical overlap in this group of autosomal dominant syndromes caused by p63 mutations and demonstrates that there are exceptions in the previously established p63 genotype-phenotype correlation.

Kallmann syndrome (hypogonadotropism-anosmia) and Klippel-Feil anomaly in the same patient.

A 27-year-old female is described with Kallman syndrome and Klippel-Feil anomaly. This is thought to be the first report of the coexistence of these two conditions in the same patient.

[Genetic heterogeneity and phenotypic variability in 46,XY sex reversal]. / Heterogeneidad genética y variabilidad fenotípica en la reversión sexual 46,XY.

The discordance between the chromosomic and the gonadal-phenotypic sex is known as sex reversal (XX males and XY females). We review the XY pure gonadal dysgenesis characterized by female phenotype, primary amenorrhea and absence of secondary sexual development. Bilateral streak gonads are always present in the complete form of this syndrome, while variable degrees of virilization are found in the partial forms, depending on the severity of the testicular damage. A plausible explanation for this pathology are SRY mutations that interfere with the testicular differentiation. However, only 10-15% of the patients with the complete form show SRY mutations, particularly in the HMG box. The remaining cases are probably due to mutations in different autosomal or X-linked genes which are also involved in the sex differentiation cascade. Recently, it has been shown that mutations in several genes responsible of well known genetic entities as WT1, SOX9, DSS and SF1, result in sex reversal. These findings reveal the genetic heterogeneity and clinical variability of XY sex reversal and provide the basis establishing a hierarchy of genes and their participation in the sex determination pathway.

A novel gene mutation in PANK2 in a patient with an atypical form of pantothenate kinase-associated neurodegeneration.

Pantothenate kinase-associated neurodegeneration (PKAN) disease is an autosomal recessive neurodegenerative disorder with iron storage in the brain due to PANK2 gene mutations. Brain magnetic resonance imaging (MRI) shows the typical "eye-of-the-tiger" sign. The aim of the present study was to describe clinical, MRI and molecular findings in a 26-year-old male with atypical PKAN disease in whom, brain MRI scans showed bilateral pallidal T2-hypointensity with a small central region of T2-hyperintensity, resembling the "eye-of-the-tiger" typical image. Genetic analysis identified two mutations in PANK2: c.1561G>A and c.1663G>A, being the latter never described before. Due to limited phenotype-genotype correlation among patients with movement disorders, if "eye-of-the-tiger" brain MRI is present, PANK2 mutations investigation are needed to confirm PKAN disease.

A Novel De Novo EFNB1 Gene Mutation in a Mexican Patient with Craniofrontonasal Syndrome.

Craniofrontonasal syndrome (CNFS) is an X-linked disorder caused by mutations in the EFNB1 gene in which, paradoxically, heterozygous females are more severely affected than hemizygous males. In this paper, the clinical and molecular studies of a female subject with CFNS are described. A novel de novo c.473T>C (p.M158T) mutation in exon 3 of EFNB1 was demonstrated in this patient. The M158 residue of the Ephrin-B1 protein is highly conserved between species. Our results expand the mutational spectrum exposed by CNFS.