RESUMO
Reports of dysferlinopathy have suggested a clinically heterogeneous group of patients. We identified specific novel molecular and phenotypic features that help distinguish dysferlinopathies from other forms of limb-girdle muscular dystrophy (LGMD). A detailed history, physical exam, and protein and mutation analysis of genomic DNA was done for all subjects. Five of 21 confirmed DYSF gene mutations were not previously reported. A distinct "bulge" of the deltoid muscle in combination with other findings was a striking feature in all patients. Six subjects had atypical calf enlargement, and 3 of these exhibited a paradoxical pattern of dysferlin expression: severely reduced by direct immunofluorescence with overexpression on Western blots. Six patients showed amyloid deposits in muscle that extended these findings to new domains of the dysferlin gene, including the C2G domain. Correlative studies showed colocalization of amyloid with deposition of dysferlin. The present data further serve to guide clinicians facing the expensive task of molecular characterization of patients with an LGMD phenotype.
Assuntos
Proteínas de Membrana/genética , Proteínas Musculares/genética , Distrofia Muscular do Cíngulo dos Membros/diagnóstico , Distrofia Muscular do Cíngulo dos Membros/genética , Adolescente , Adulto , Amiloide/metabolismo , Biópsia , Western Blotting , Criança , Pré-Escolar , Estudos de Coortes , DNA/genética , Disferlina , Feminino , Técnica Direta de Fluorescência para Anticorpo , Humanos , Imuno-Histoquímica , Perna (Membro)/patologia , Masculino , Monócitos/química , Músculo Esquelético/patologia , Distrofia Muscular do Cíngulo dos Membros/patologia , Mutação/fisiologia , Fenótipo , Adulto JovemRESUMO
Recent studies have shown that certain copy number variations (CNV) are associated with a wide range of neurodevelopmental disorders, including autism spectrum disorders (ASD), bipolar disorder and intellectual disabilities. Implicated regions and genes have comprised a variety of post synaptic complex proteins and neurotransmitter receptors, including gamma-amino butyric acid A (GABAA). Clusters of GABAA receptor subunit genes are found on chromosomes 4p12, 5q34, 6q15 and 15q11-13. Maternally inherited 15q11-13 duplications among individuals with neurodevelopmental disorders are well described, but few case reports exist for the other regions. We describe a family with a 2.42 Mb duplication at chromosome 4p13 to 4p12, identified in the index case and other family members by oligonucleotide array comparative genomic hybridization, that contains 13 genes including a cluster of four GABAA receptor subunit genes. Fluorescent in-situ hybridization was used to confirm the duplication. The duplication segregates with a variety of neurodevelopmental disorders in this family, including ASD (index case), developmental delay, dyspraxia and ADHD (brother), global developmental delays (brother), learning disabilities (mother) and bipolar disorder (maternal grandmother). In addition, we identified and describe another individual unrelated to this family, with a similar duplication, who was diagnosed with ASD, ADHD and borderline intellectual disability. The 4p13 to 4p12 duplication appears to confer a susceptibility to a variety of neurodevelopmental disorders in these two families. We hypothesize that the duplication acts through a dosage effect of GABAA receptor subunit genes, adding evidence for alterations in the GABAergic system in the etiology of neurodevelopmental disorders.
Assuntos
Transtornos Globais do Desenvolvimento Infantil/genética , Hibridização Genômica Comparativa , Variações do Número de Cópias de DNA/genética , Deficiências do Desenvolvimento/genética , Receptores de GABA-A/genética , Adulto , Criança , Transtornos Globais do Desenvolvimento Infantil/etiologia , Transtornos Globais do Desenvolvimento Infantil/patologia , Pré-Escolar , Cromossomos Humanos Par 4/genética , Deficiências do Desenvolvimento/etiologia , Deficiências do Desenvolvimento/patologia , Feminino , Duplicação Gênica , Humanos , Hibridização in Situ Fluorescente , Masculino , Linhagem , FenótipoRESUMO
Structural and sequence variation have been described in several members of the contactin (CNTN) and contactin-associated protein (CNTNAP) gene families in association with neurodevelopmental disorders, including autism. Using array comparative genome hybridization (CGH), we identified a maternally inherited â¼535 kb deletion at 3p26.3 encompassing the 5' end of the contactin 4 gene (CNTN4) in a patient with autism. Based on this finding and previous reports implicating genomic rearrangements of CNTN4 in autism spectrum disorders (ASDs) and 3p- microdeletion syndrome, we undertook sequencing of the coding regions of the gene in a local ASD cohort in comparison with a set of controls. Unique missense variants were identified in 4 of 75 unrelated individuals with ASD, as well as in 1 of 107 controls. All of the amino acid substitutions were nonsynonomous, occurred at evolutionarily conserved positions, and were, thus, felt likely to be deleterious. However, these data did not reach statistical significance, nor did the variants segregate with disease within all of the ASD families. Finally, there was no detectable difference in binding of two of the variants to the interacting protein PTPRG in vitro. Thus, additional larger studies will be necessary to determine whether CNTN4 functions as an autism susceptibility locus in combination with other genetic and/or environmental factors.