A novel GPR143 duplication mutation in a Chinese family with X-linked congenital nystagmus

PURPOSE To elucidate the molecular genetic defect of X-linked congenital nystagmus in a Chinese family. METHODS Genomic DNA was prepared from peripheral blood. We used allele-sharing analysis to identify the possible locus harboring the disease-causing gene. We screened for mutations in the G protein-coupled receptor 143 gene (GPR143) by direct sequencing of the polymerase chain reaction (PCR)-amplified exons. RESULTS In analyzing the candidate gene, GPR143, in the linked region, a 19 base pair (bp) duplication mutation in exon 1 was detected after direct DNA sequence analysis, which cosegregated in all patients of this family and was present in obligate female carriers. CONCLUSIONS The identified 19 bp duplication in GPR143 induces a frame-shift and a premature stop codon, resulting in a truncated protein of 105 residues. These results suggest that this novel mutation is associated with the congenital nystagmus observed in this Chinese family and further support that GPR143 mutations are the underlying pathogenesis of the molecular mechanism for congenital nystagmus.