A novel frame-shift mutation in FRMD7 causes X-linked idiopathic congenital nystagmus in a Chinese family

PURPOSE To screen mutations in the FERM domain-containing 7 (FRMD7) gene in a Chinese family with X-linked idiopathic congenital nystagmus (ICN). METHODS It has been reported that FRMD7 mutations account for approximately 47% of X-linked nystagmus in Chinese patients. We collected 5 ml of blood samples from members of a family with X-linked ICN and 100 normal controls. Mutations in FRMD7 were determined by sequencing PCR products. RESULTS We identified a previously unreported 4 bp deletion in FRMD7 (c.1486-1489 del TTTT) in a Chinese family. The mutation co-segregated with the disease phenotype in patients and female carriers, while it was not detected in other relatives or in the 100 normal controls. CONCLUSIONS Our results expand the spectrum of FRMD7 mutations causing ICN, and further confirm the role of FRMD7 in the pathogenesis of ICN. Direct sequencing of FRMD7 could be used as a diagnostic testing of idiopathic congenital nystagmus.