RESUMEN
PURPOSE: The short arm of chromosome 16 is rich in segmental duplications, predisposing this region of the genome to a number of recurrent rearrangements. Genomic imbalances of an approximately 600-kb region in 16p11.2 (29.5-30.1 Mb) have been associated with autism, intellectual disability, congenital anomalies, and schizophrenia. However, a separate, distal 200-kb region in 16p11.2 (28.7-28.9 Mb) that includes the SH2B1 gene has been recently associated with isolated obesity. The purpose of this study was to better define the phenotype of this recurrent SH2B1-containing microdeletion in a cohort of phenotypically abnormal patients not selected for obesity. METHODS: Array comparative hybridization was performed on a total of 23,084 patients in a clinical setting for a variety of indications, most commonly developmental delay. RESULTS: Deletions of the SH2B1-containing region were identified in 31 patients. The deletion is enriched in the patient population when compared with controls (P = 0.003), with both inherited and de novo events. Detailed clinical information was available for six patients, who all had developmental delays of varying severity. Body mass index was ≥95th percentile in four of six patients, supporting the previously described association with obesity. The reciprocal duplication, found in 17 patients, does not seem to be significantly enriched in our patient population compared with controls. CONCLUSIONS: Deletions of the 16p11.2 SH2B1-containing region are pathogenic and are associated with developmental delay in addition to obesity.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Cromosomas Humanos Par 16/genética , Discapacidades del Desarrollo/genética , Obesidad/genética , Eliminación de Secuencia , Anomalías Múltiples/genética , Índice de Masa Corporal , Preescolar , Hibridación Genómica Comparativa , Variaciones en el Número de Copia de ADN , Dosificación de Gen , Estudio de Asociación del Genoma Completo , Humanos , Lactante , Recién Nacido , Discapacidad Intelectual/genética , Hibridación de Ácido Nucleico , Fenotipo , Duplicaciones Segmentarias en el GenomaRESUMEN
PURPOSE: To report results of linkage analysis in a large family with autosomal dominant (AD) febrile seizures (FS) and epilepsy. BACKGROUND: AD FS and epilepsy is clinically and genetically a heterogeneous group of epilepsies, frequently inherited. The most notable, generalized epilepsy with febrile seizures plus (GEFS+), is characterized by heterogeneous phenotypes including FS persisting beyond the usual age of remission or coexisting with afebrile seizures. Mutations in three subunits of sodium channel genes and one GABA(A)-receptor subunit gene have been identified in some GEFS+ pedigrees. Six genetic loci for FS have been reported so far, but the molecular basis of FS remains unknown. METHODS: We identified a five-generation family with 13 individuals affected by FS. Evidence was found for coexisting afebrile seizures in some affected individuals. Evaluation included a detailed history and neurologic examination, as well as collection of DNA. After excluding previously identified loci associated with FS and epilepsy, a genome-wide search was performed. RESULTS: Two affected individuals reported only a single FS, whereas the other affected individuals had a history of repeated FS. Coexisting afebrile seizures developed in three individuals. The mode of inheritance was consistent with AD inheritance with an incomplete penetrance. Tight linkage to a group of markers on chromosome 21q22 was identified with flanking markers D21S1909 and D21S1444, and maximum 2-point lod score 3.35 for markers D21S1910 and D21S1894. We excluded four ion-channel genes within this 6.5-cM locus as a cause of FS and epilepsy in this family. CONCLUSIONS: We report a novel locus on chromosome 21q22 for AD FS. Identification of the gene causing epilepsy on chromosome 21q22 will advance our understanding of inherited epilepsy and FS, and possibly other types of epilepsies.