Identification of a novel missense mutation in RAD51 in a large family with congenital mirror movements
Onat, Onur Emre
Dal, G. M.
62nd Annual Meeting of the American Society of Human Genetics, ASHG 2012
American Society of Human Genetics
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Congenital mirror movements (CMM) are a rare and heterogeneous group of disorders characterized by involuntary contralateral movements of mainly the upper extremities during intentional movements on the opposite side. Isolated cases are usually familial and suggest autosomal dominant inheritance with incomplete penetrance. In two chromosome 18 linked families, causative mutations were identified in DCC (Science 328:592, 2010; MRMV1; MIM:157600). Here, we describe a three-generation consanguineous Turkish family with six members affected by CMM. Linkage analysis with a dominant model and 90 percent penetrance parameters resulted in peaks on 15q13.3-q21.1, 15q26.2, and 19q12 with maximum multipoint LOD scores of 3.6, 2.6, and 2.6, respectively. However, a region of homozygosity segregating with the phenotype was not observed, and thus excluded the possibility of recessive inheritance of the disease allele in this consanguineous family. Whole-exome sequencing of an affected individual uncovered 7 coding, 33 intronic and 3 intergenic novel variants located within the three linkage intervals, which were filtered against the dbSNP132 dataset. Segregation analysis, population filtering using 1000 genomes and EVS data sets, and conservation considerations using prediction tools revealed a novel missense mutation (c.404C>T [p.T134N], RefSeq accession number NM_002875) in exon 5 of RAD51 (MIM:179617), consistent with the dominant inheritance of the disease allele in the family. The mutation resides in the highly conserved AAA (ATPases associated with diverse cellular activities) domain of the protein, and it was not observed in 436 chromosomes from healthy individuals coming from a geographical matched region. Recently, truncating mutations in RAD51 were identified in two families with CMM (Am J Hum Genet 90:301,2012; MRMV2; MIM:614508). Our findings support the totally unexpected role of RAD51 in neurodevelopment and further suggest that alterations of this gene may lead to neurological phenotypes.