Clinical And Genetic Analysis In 56 Chinese Patients With Leler Congenital Amaurosis

Objective:To analyze clinical phenotype characteristics and genetic features of Leber congenital amaurosis;and to screen the potential and known disease- causing genetic mutation loci about Leber congenital amaurosis.Methods:In this study, the clinical data of patients with Leber congenital amaurosis were collected and analyzed. We collected the venous blood samples from patients and health members in the very same families, and then extracted the genome DNA from these blood samples. By using polymerase chain reaction (PCR), we amplified the disease- causing genes leading to Leber congenital amaurosis, including all the exons and exon– intron layups of retinal pigment epithelium (RPE65) gene and lecithin retinol acyltransferase (LRAT)gene, followed directly by sequencing and identifying the disease-causing mutant genes. Since determining the disease- causing mutations, in order to judging whether or not these mutations are normal known polymorphic sites, first of all, we performed single nucleotide polymorphism analysis for these mutations (www. ncbi. nlm. nih. gov/ snp). And then, through inquiring the relevant document published in foreign journals, we determined whether or not these mutation loci found in our study had been reported by others. In the last, if these mutations found in our study were judged as new ones, for the purpose to exclude the potential that these mutations we found were some unknown population polymorphisms, it still needed to amplify these mutations by PCR and sequence them with at least 50 normal subjects (100 chromosomes) without any consanguinity relationship.Results:Through testing 14 exons in RPE65 gene and 3 exons in LRAT genes in 56 patients, we found 7 new changes about single nucleotide polymorphism. In our study, we found that a new single nucleotide polymorphism existed cbefore the third exon in RPE65 gene in 1 case; a new single nucleotide polymorphism existed before the tenth exon in RPE65 gene in 26 cases; and 27 patients had a new single nucleotide polymorphism before the twelveth exon in RPE65 gene; 9 patients had a new single nucleotide polymorphism before the fourteenth exon in RPE65 gene; and also in 5 cases before the 2a exon in LRAT gene there was a new single nucleotide polymorphism; in 11 cases efore the 2bF exon in LRAT gene there was a new single nucleotide polymorphism. Conclusion:The clinical patterns of Leber congenital amaurosis are various, and the clinical diagnosis depends on the synthetic judgment based on the clinical patterns, fundus appearance and all kinds of auxiliary examinations. In our study, all the 56 cases have no significant correlation with mutations of RPE65 exons and LRAT exons, which means that these exons are unlikely to influence patients with Leber congenital amaurosis. And these same single nucleotide polymorphism changes found in different patients with Leber congenital amaurosis may have certain clinical values and basic research meanings. So for the further study we should increase samples and analyze the protein functions deeply.