FLNA genomic rearrangements cause periventricular nodular heterotopia.

OBJECTIVE: To identify copy number variant (CNV) causes of periventricular nodular heterotopia (PNH) in patients for whom FLNA sequencing is negative. METHODS: Screening of 35 patients from 33 pedigrees on an Affymetrix 6.0 microarray led to the identification of one individual bearing a CNV that disrupted FLNA. FLNA-disrupting CNVs were also isolated in 2 other individuals by multiplex ligation probe amplification. These 3 cases were further characterized by high-resolution oligo array comparative genomic hybridization (CGH), and the precise junctional breakpoints of the rearrangements were identified by PCR amplification and sequencing. RESULTS: We report 3 cases of PNH caused by nonrecurrent genomic rearrangements that disrupt one copy of FLNA. The first individual carried a 113-kb deletion that removes all but the first exon of FLNA. A second patient harbored a complex rearrangement including a deletion of the 3' end of FLNA accompanied by a partial duplication event. A third patient bore a 39-kb deletion encompassing all of FLNA and the neighboring gene EMD. High-resolution oligo array CGH of the FLNA locus suggests distinct molecular mechanisms for each of these rearrangements, and implicates nearby low copy repeats in their pathogenesis. CONCLUSIONS: These results demonstrate that FLNA is prone to pathogenic rearrangements, and highlight the importance of screening for CNVs in individuals with PNH lacking FLNA point mutations.

C2orf37 mutational spectrum in Woodhouse-Sakati syndrome patients.

Woodhouse-Sakati syndrome (WSS) is a rare autosomal recessive disorder that encompasses hypogonadism, deafness, alopecia, mental retardation, diabetes mellitus and progressive extrapyramidal defects. The syndrome is caused by mutation of the C2orf37 gene. Here we studied a cohort of seven new cases from three ethnic backgrounds, presenting with the hallmarks of WSS, in an effort to extend the mutational spectrum of this disorder. Genetic analysis revealed a novel mutation in each of the four families investigated, of which three were nonsense mutations and the fourth was a splice site ablation. We also examined a separate collection of 11 cases presenting with deafness and dystonia, two constituents of WSS, but found no pathogenic changes. This study doubles the number of known mutations for this disorder, confirms that truncating mutations in C2orf37 are the only known cause of WSS, and suggests that mutations in this gene do not contribute significantly to cases presenting with isolated elements of WSS such as deafness and dystonia. The lack of correlation between clinically expressivity of WSS and the site of the eight truncating mutations strongly supports that they are equally null, while the intrafamilial variability argues for an important role of modifiers in this disease.

VACTERL manifestations in two generations of a family.

Most cases of the VACTERL "association" [Martinez-Frias et al., Am. J. Med. Genet. 76: 291-296, 1998] are sporadic, with an empiric recurrence risk of 1% or less. Rare families with recurrence of VACTERL-H association are described with patterns consistent with single gene inheritance. Also described are occasional single anomalies of the VACTERL association in sibs or parents of affected individuals. We describe a mother and son with typical VACTERL anomalies. The patient was born by cesarean section to a 27-year-old G1 mother following an uncomplicated pregnancy. He was found to have an asymmetric crying face, preaxial polydactyly on the right, a small midmuscular ventricular septal defect with an incomplete right bundle branch block on echocardiogram, a small cleft in T3, and incomplete development of the left half of the sacrum. The kidneys were normal ultrasonographically. The patient's mother was born with an H-type tracheo-esophageal fistula, imperforate anus, rectovaginal fistula, a triphalangeal thumb, hypoplastic left kidney, and vertebral anomalies. There were no other individuals with VACTERL anomalies in the family. No families with VACTERL association in the offspring of an affected individual have been reported previously.