OBJECTIVE: To study the disease-causing gene for a Chinese family with X-linked congenital idiopathic nystagmus. METHODS: It was a retrospective study. The phenotype of a Chinese family with congenital nystagmus was identified by investigating the history and the clinical features of each family member. The mode of inheritance in this family was ascertained by the pedigree analysis. Linkage analysis was performed to identify the possible locus harboring the disease-causing gene. Direct DNA sequence analysis was performed to find the mutation responsible for this disease. RESULTS: The positive LOD score was obtained for 10 microsatellite makers on chromosome Xq25-Xq27, and the maximum LOD score with DXS1211 was 3.91. A 2-bp deletion in exon 8 of FRMD7 was detected after direct DNA sequence analysis, which was cosegregated with all patients in this family. CONCLUSION: Congenital nystagmus is a clinically and genetically heterogeneous ocular movement disease. Mutation of the FRMD7 gene is the cause of congenital nystagmus in this family.
OBJECTIVE: To study the disease-causing gene for a Chinese family with X-linked congenital idiopathic nystagmus. METHODS: It was a retrospective study. The phenotype of a Chinese family with congenital nystagmus was identified by investigating the history and the clinical features of each family member. The mode of inheritance in this family was ascertained by the pedigree analysis. Linkage analysis was performed to identify the possible locus harboring the disease-causing gene. Direct DNA sequence analysis was performed to find the mutation responsible for this disease. RESULTS: The positive LOD score was obtained for 10 microsatellite makers on chromosome Xq25-Xq27, and the maximum LOD score with DXS1211 was 3.91. A 2-bp deletion in exon 8 of FRMD7 was detected after direct DNA sequence analysis, which was cosegregated with all patients in this family. CONCLUSION:Congenital nystagmus is a clinically and genetically heterogeneous ocular movement disease. Mutation of the FRMD7 gene is the cause of congenital nystagmus in this family.