Description of the molecular and clinical characteristics of the mucopolysaccharidosis type VII Iberian cohort.

BACKGROUND: Mucopolysaccharidosis type VII (Sly syndrome) is an ultra-rare neurometabolic disorder caused by inherited deficiency of the lysosomal enzyme ß-glucuronidase. Precise data regarding its epidemiology are scarce, but birth prevalence is estimated to vary from 0.02 to 0.24 per 100,000 live births. The clinical course and disease progression are widely heterogeneous, but most patients have been reported to show signs such as skeletal deformities or cognitive delay. Additionally, detection criteria are not standardized, resulting in delayed diagnosis and treatment. METHODS: We present a cohort of 9 patients with mucopolysaccharidosis VII diagnosed in the Iberian Peninsula, either in Spain or Portugal. The diagnostic approach, genetic studies, clinical features, evolution and treatment interventions were reviewed. RESULTS: We found that skeletal deformities, hip dysplasia, hydrops fetalis, hepatosplenomegaly, hernias, coarse features, respiratory issues, and cognitive and growth delay were the most common features identified in the cohort. In general, patients with early diagnostic confirmation who received the appropriate treatment in a timely manner presented a more favorable clinical evolution. CONCLUSIONS: This case series report helps to improve understanding of this ultra-rare disease and allows to establish criteria for clinical suspicion or diagnosis, recommendations, and future directions for better management of patients with Sly syndrome.

Accuracy diagnosis improvement of Fabry disease from dried blood spots: Enzyme activity, lyso-Gb3 accumulation and GLA gene sequencing.

The purpose of this study was to examine the applicability of the use of samples in dried blood spot (DBS) for the definitive diagnosis of Fabry disease (FD) in males and females and to compare the diagnostic role of α-galactosidase A activity (α-Gal A), levels of lyso-Gb3 and sequencing of the GLA gene in screening patients with suspected FD. Measurement of α-Gal A activity in suspected FD patients in DBS was made followed by lyso-Gb3 determination and GLA gene sequencing. Of the 2381 subjects analyzed, FD was confirmed in 24 patients. Thirteen different variants were considered like pathogenic, five of which had not been previously described (c.143A > G; c.455A > C; c.487G > T; c.554delA; c.1045_1046insA). None of the patients with normal enzyme activity had FD confirmation. The DBS measurement of α-Gal A was more sensitive than lyso-Gb3 levels in both men and women. Definitive diagnosis of FD from a single DBS is possible, allowing samples to be easily sent from anywhere to the reference laboratory.

Expanding the clinical and mutational spectrum of germline ABL1 mutations-associated syndrome: A case report.

RATIONALE: Clinical and genetic management of patients with rare syndromes is often a difficult, confusing, and slow task. PATIENT CONCERNS: Male child patient with a multisystemic disease showing congenital heart defects, facial dysmorphism, skeletal malformations, and eye anomalies. DIAGNOSIS: The patient remained clinically undiagnosed until the genetic results were conclusive and allowed to associate its clinical features with the germline ABL1 mutations-associated syndrome. INTERVENTIONS: We performed whole-exome sequencing to uncover the underlying genetic defect in this patient. Subsequently, family segregation of identified mutations was performed by Sanger sequencing in all available family members. OUTCOMES: The only detected variant compatible with the disease was a novel heterozygous nonframeshift de novo deletion in ABL1 (c.434_436del; p.Ser145del). The affected residue lays in a functional domain of the protein, it is highly conserved among distinct species, and its loss is predicted as pathogenic by in silico studies. LESSONS: Our results reinforce the involvement of ABL1 in clinically undiagnosed cases with developmental defects and expand the clinical and genetic spectrum of the recently reported ABL1-associated syndrome. In this sense, we described the third germline ABL1 causative mutation and linked, for the first time, ocular anterior chamber anomalies to this pathology. Thus, we suggest that this disorder may be more heterogeneous than is currently believed and may be overlapping with other multisystemic diseases, hence genetic and clinical reassessment of this type of cases should be considered to ensure proper diagnosis.

ACTB Loss-of-Function Mutations Result in a Pleiotropic Developmental Disorder.

ACTB encodes ß-actin, an abundant cytoskeletal housekeeping protein. In humans, postulated gain-of-function missense mutations cause Baraitser-Winter syndrome (BRWS), characterized by intellectual disability, cortical malformations, coloboma, sensorineural deafness, and typical facial features. To date, the consequences of loss-of-function ACTB mutations have not been proven conclusively. We describe heterozygous ACTB deletions and nonsense and frameshift mutations in 33 individuals with developmental delay, apparent intellectual disability, increased frequency of internal organ malformations (including those of the heart and the renal tract), growth retardation, and a recognizable facial gestalt (interrupted wavy eyebrows, dense eyelashes, wide nose, wide mouth, and a prominent chin) that is distinct from characteristics of individuals with BRWS. Strikingly, this spectrum overlaps with that of several chromatin-remodeling developmental disorders. In wild-type mouse embryos, ß-actin expression was prominent in the kidney, heart, and brain. ACTB mRNA expression levels in lymphoblastic lines and fibroblasts derived from affected individuals were decreased in comparison to those in control cells. Fibroblasts derived from an affected individual and ACTB siRNA knockdown in wild-type fibroblasts showed altered cell shape and migration, consistent with known roles of cytoplasmic ß-actin. We also demonstrate that ACTB haploinsufficiency leads to reduced cell proliferation, altered expression of cell-cycle genes, and decreased amounts of nuclear, but not cytoplasmic, ß-actin. In conclusion, we show that heterozygous loss-of-function ACTB mutations cause a distinct pleiotropic malformation syndrome with intellectual disability. Our biological studies suggest that a critically reduced amount of this protein alters cell shape, migration, proliferation, and gene expression to the detriment of brain, heart, and kidney development.

Heterogeneity of a Constitutional Complex Chromosomal Rearrangement in 2q.

Complex chromosome rearrangements (CCRs) are unusual structural chromosome alterations found in humans, and to date only a few have been characterized molecularly. New mechanisms, such as chromothripsis, have been proposed to explain the presence of the CCRs in cancer cells and in patients with congenital disorders and/or mental retardation. The aim of the present study was the molecular characterization of a constitutional CCR in a girl with multiple congenital disorders and intellectual disability in order to determine the genotype-phenotype relation and to clarify whether the CCR could have been caused by chromosomal catastrophic events. The present CCR was characterized by G-banding, high-resolution CGH, multiplex ligation-dependent probe amplification and subtelomeric 2q-FISH analyses. Preliminary results indicate that the de novo CCR is unbalanced showing a 2q37.3 deletion and 2q34q37.2 partial trisomy. Our patient shows some of the typical traits and intellectual disability described in patients with 2q37 deletion and also in carriers of 2q34q37.2 partial trisomy; thus, the clinical disorders could be explained by additional effects of both chromosome alterations (deletions and duplications). A posterior, sequential FISH study using BAC probes revealed the unexpected presence of at least 17 different reorganizations affecting 2q34q37.2, suggesting the existence of chromosome instability in this region. The present CCR is the first case described in the literature of heterogeneity of unbalanced CCRs affecting a small region of 2q, indicating that the mechanisms involved in constitutional chromosome rearrangement may be more complex than previously thought.

Clinical course of sly syndrome (mucopolysaccharidosis type VII).

BACKGROUND: Mucopolysaccharidosis VII (MPS VII) is an ultra-rare disease characterised by the deficiency of ß-glucuronidase (GUS). Patients' phenotypes vary from severe forms with hydrops fetalis, skeletal dysplasia and mental retardation to milder forms with fewer manifestations and mild skeletal abnormalities. Accurate assessments on the frequency and clinical characteristics of the disease have been scarce. The aim of this study was to collect such data. METHODS: We have conducted a survey of physicians to document the medical history of patients with MPS VII. The survey included anonymous information on patient demographics, family history, mode of diagnosis, age of onset, signs and symptoms, severity, management, clinical features and natural progression of the disease. RESULTS: We collected information on 56 patients from 11 countries. Patients with MPS VII were classified based on their phenotype into three different groups: (1) neonatal non-immune hydrops fetalis (NIHF) (n=10), (2) Infantile or adolescent form with history of hydrops fetalis (n=13) and (3) Infantile or adolescent form without known hydrops fetalis (n=33). Thirteen patients with MPS VII who had the infantile form with history of hydrops fetalis and survived childhood, had a wide range of clinical manifestations from mild to severe. Five patients underwent bone marrow transplantation and one patient underwent enzyme replacement therapy with recombinant human GUS. CONCLUSIONS: MPS VII is a pan-ethnic inherited lysosomal storage disease with considerable phenotypical heterogeneity. Most patients have short stature, skeletal dysplasia, hepatosplenomegaly, hernias, cardiac involvement, pulmonary insufficiency and cognitive impairment. In these respects it resembles MPS I and MPS II. In MPS VII, however, one unique and distinguishing clinical feature is the unexpectedly high proportion of patients (41%) that had a history of NIHF. Presence of NIHF does not, by itself, predict the eventual severity of the clinical course, if the patient survives infancy.

[Combined methylmalonic acidemia and homocystinuria; a case report]. / Combinación de acidemia metilmalónica y homocisteinuria; a propósito de un caso.

Combined methylmalonic acidemia and homocystinuria is an inborn error of metabolism of vitamin B12 or cobalamin. It's a rare autosomal recessive disease in which there are several variants depending on the pathogenesis of the metabolic disorder (cblC, cblD, cblF and cblJ). The more frequent and more severe is the cblC variant, which usually manifests in the first months of life, although some cases have been reported at the beginning of adulthood. A proper diagnosis and effective therapeutic approach is fundamental. We report the case of a patient of 18 years with a history of epilepsy who consults for acute renal failure requiring renal replacement therapy and diagnosed with combined methylmalonic acidemia and homocystinuria cblC variant.

La combinación de homocistinuria con acidemia metilmalónica es un error congénito del metabolismo de la vitamina B12 o cobalamina. Es una patología poco frecuente de herencia autosómica recesiva en la que existen diversas variantes en función de la patogenia del trastorno metabólico (cblC, cblD, cblF y cblJ). La más frecuente y más grave es la variante cblC, que suele manifestarse en los primeros meses de vida, aunque se han reportado casos al inicio de la edad adulta. Se hace fundamental un correcto diagnóstico y un abordaje terapéutico eficaz. Presentamos el caso clínico de una paciente de 18 años con antecedentes personales de epilepsia que acude por fracaso renal agudo con necesidad de terapia renal sustitutiva diagnosticándose de homocistinuria con acidemia metilmalónica variante cblC.

[Cardiofaciocutaneous syndrome, a Noonan syndrome related disorder: clinical and molecular findings in 11 patients]. / Síndrome cardiofaciocutáneo, un trastorno relacionado con el síndrome de Noonan: hallazgos clínicos y moleculares en 11 pacientes.

OBJECTIVES: To describe 11 patients with cardiofaciocutaneous syndrome (CFC) and compare them with 130 patients with other RAS-MAPK syndromes (111 Noonan syndrome patients [NS] and 19 patients with LEOPARD syndrome). PATIENTS AND METHODS: Clinical data from patients submitted for genetic analysis were collected. Bidirectional sequencing analysis of PTPN11, SOS1, RAF1, BRAF, and MAP2K1 focused on exons carrying recurrent mutations, and of all KRAS exons were performed. RESULTS: Six different mutations in BRAF were identified in 9 patients, as well as 2 MAP2K1 mutations. Short stature, developmental delay, language difficulties and ectodermal anomalies were more frequent in CFC patients when compared with other neuro-cardio-faciocutaneous syndromes (P<.05). In at least 2 cases molecular testing helped reconsider the diagnosis. DISCUSSION: CFC patients showed a rather severe phenotype but at least one patient with BRAF mutation showed no developmental delay, which illustrates the variability of the phenotypic spectrum caused by BRAF mutations. Molecular genetic testing is a valuable tool for differential diagnosis of CFC and NS related disorders.

Atypical Association of Angelman Syndrome and Klinefelter Syndrome in a Boy with 47,XXY Karyotype and Deletion 15q11.2-q13.

Angelman syndrome (AS, OMIM 105830) is a neurogenetic disorder with firm clinical diagnostic guidelines, characterized by severe developmental delay and speech impairment, balanced and behavioral disturbance as well as microcephaly, seizures, and a characteristic electroencephalogram (EEG). The majority of AS cases (70%) are caused by a 15q11.2-q13 deletion on the maternally derived chromosome. The frequency of AS has been estimated to be between 1/10000 and 1/20000. Klinefelter syndrome (KS) occurs due to the presence of an extra X chromosome (karyotype 47,XXY). The main features in KS are small testes, hypergonadotropic hypogonadism, gynecomastia, learning difficulties, and infertility. We present what is, to our knowledge, the first case of a patient with both KS and AS due to a 15q11.2-q13 deletion on the maternally derived chromosome and an extra X chromosome of paternal origin. He showed dysmorphic features, axial hypotonia, and delayed acquisition of motor skills. Early diagnosis is essential for optimal treatment of AS children; this is one of the earliest diagnosed cases of AS probably due to the presence of two syndromes. Clinical findings in this patient here described may be helpful to identify any other cases and to evaluate recurrence risks in these families.

Mutation prevalence of cerebral cavernous malformation genes in Spanish patients.

OBJECTIVE: To study the molecular genetic and clinical features of cerebral cavernous malformations (CCM) in a cohort of Spanish patients. METHODS: We analyzed the CCM1, CCM2, and CCM3 genes by MLPA and direct sequencing of exons and intronic boundaries in 94 familial forms and 41 sporadic cases of CCM patients of Spanish extraction. When available, RNA studies were performed seeking for alternative or cryptic splicing. RESULTS: A total of 26 pathogenic mutations, 22 of which predict truncated proteins, were identified in 29 familial forms and in three sporadic cases. The repertoire includes six novel non-sense and frameshift mutations in CCM1 and CCM3. We also found four missense mutations, one of them located at the third NPXY motif of CCM1 and another one that leads to cryptic splicing of CCM1 exon 6. We found four genomic deletions with the loss of the whole CCM2 gene in one patient and a partial loss of CCM1and CCM2 genes in three other patients. Four families had mutations in CCM3. The results include a high frequency of intronic variants, although most of them localize out of consensus splicing sequences. The main symptoms associated to clinical debut consisted of cerebral haemorrhage, migraines and epileptic seizures. The rare co-occurrence of CCM with Noonan and Chiari syndromes and delayed menarche is reported. CONCLUSIONS: Analysis of CCM genes by sequencing and MLPA has detected mutations in almost 35% of a Spanish cohort (36% of familial cases and 10% of sporadic patients). The results include 13 new mutations of CCM genes and the main clinical symptoms that deserves consideration in molecular diagnosis and genetic counselling of cerebral cavernous malformations.

Contributions of PHOX2B in the pathogenesis of Hirschsprung disease.

Hirschsprung disease (HSCR) is a congenital malformation of the hindgut resulting from a disruption of neural crest cell migration during embryonic development. It has a complex genetic aetiology with several genes involved in its pathogenesis. PHOX2B plays a key function in the development of neural crest derivatives, and heterozygous mutations cause a complex dysautonomia associating HSCR, Congenital Central Hypoventilation Syndrome (CCHS) and neuroblastoma (NB) in various combinations. In order to determine the role of PHOX2B in isolated HSCR, we performed a mutational screening in a cohort of 207 Spanish HSCR patients. Our most relevant finding has been the identification of a de novo and novel deletion (c.393_410del18) in a patient with HSCR. Results of in silico and functional assays support its pathogenic effect related to HSCR. Therefore our results support that PHOX2B loss-of-function is a rare cause of HSCR phenotype.

Macrocephaly-capillary malformation: Analysis of 13 patients and review of the diagnostic criteria.

Macrocephaly-capillary malformation (M-CM) is a genetic syndrome of unknown etiology characterized by an enlarged head circumference and patchy, reticular capillary malformation. We describe the clinical features of 13 cases, report on the genome-wide Copy Number Variation characterization of these patients, analyze the main clinical features of this syndrome and propose a modification of the current diagnostic criteria: the inclusion of both overgrowth/asymmetry and neuroimaging alterations as major criteria.

HRAS mutation analysis in Costello syndrome: genotype and phenotype correlation.

Costello syndrome is a rare condition comprising mental retardation, distinctive facial appearance, cardiovascular abnormalities (typically pulmonic stenosis, hypertrophic cardiomyopathy, and/or atrial tachycardia), tumor predisposition, and skin and musculoskeletal abnormalities. Recently mutations in HRAS were identified in 12 Japanese and Italian patients with clinical information available on 7 of the Japanese patients. To expand the molecular delineation of Costello syndrome, we performed mutation analysis in 34 North American and 6 European (total 40) patients with Costello syndrome, and detected missense mutations in HRAS in 33 (82.5%) patients. All mutations affected either codon 12 or 13 of the protein product, with G12S occurring in 30 (90.9%) patients of the mutation-positive cases. In two patients, we found a mutation resulting in an alanine substitution in position 12 (G12A), and in one patient, we detected a novel mutation (G13C). Five different HRAS mutations have now been reported in Costello syndrome, however genotype-phenotype correlation remains incomplete.

Clinical and molecular studies on two further families with Simpson-Golabi-Behmel syndrome.

The Simpson-Golabi-Behmel syndrome (SGBS) (OMIM 312870) is an overgrowth/multiple congenital anomalies syndrome caused by a semi-dominant X-linked gene encoding glypican 3 (GPC3). It shows great clinical variability, ranging from mild forms in carrier females to lethal forms with failure to thrive in males. The most consistent findings in SGBS are pre- and postnatal macrosomia, characteristic facial anomalies and abnormalities affecting the internal organs, skeleton, and on some occasions, mental retardation of variable degree. SGBS is also associated with an increased risk of developing embryonal tumors, mostly Wilms and liver tumors. We describe two molecularly-confirmed families with SGBS. All patients had typical manifestations of SGBS including some female relatives who had minor manifestations of the disorder. Some patients had novel findings such as a deep V-shaped sella turcica and six lumbar vertebrae. Molecular studies in affected patients showed a deletion of exon 6 in family 1 and an intronic mutation in family 2.