Identification of a COL2A1 mutation in a Chinese family with Stickler syndrome type 1 via whole exome sequencing / 中华实验眼科杂志

ABSTRACT

Objective:To identify the disease-causing mutation in a Chinese family with Stickler syndrome type 1.Methods:The pedigree investigation was conducted.A Chinese family with Stickler syndrome type 1 was enrolled in the Shantou International Eye Center in June 2012.Medical history collection and clinical examinations, such as vision, intraocular pressure, slit lamp microscopy and fundus, were carried out in all the included family members and the diagnosis was made by clinical experts.Total genomic DNAs were extracted from the peripheral blood samples (5 ml) obtained from 5 patients and 4 healthy members.The potential variant of the proband's father Ⅲ-5 were screened by whole exome sequencing (WES) and stepwise bioinformatic analysis.The segregation and mutation conformation of the variant was verified by Sanger sequencing.The pathogenicity of the variant was predicted by SIFT, Polyphen2, and MutationTaster.Conservation and three-dimensional structure of amino acid mutation were analyzed by multiple sequence alignment and UniProt.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Joint Shantou International Eye Center (No.EC20110310[2]-P02).Written informed consent was obtained from each subject or the guardian.Results:An autosomal dominant inherence in 39 members of 4 generations including 15 patients and 24 phenotypically normal members was found in the family.The proband (Ⅳ-4) showed high myopia, retinal detachment and strabismus in the right eye, and the left eye was blind.A patient (Ⅲ-5) showed high myopia and cataract in the right eye, atrophy in the left eye.A patient (Ⅳ-9) showed binocular high myopia.A heterozygous variation, c.1693C>T p.Arg565Cys, within the exon 26 of COL2A1 gene was revealed in patient Ⅲ-5, which was only found in the patients and not in phenotypically normal members, indiacating co-separation in this family.The variant was predicted to be a severe damage by SIFT, Polyphen2 and MutationTaster.The amino acid mutation at position 565 was highly conservative among human, mouse, rat, bovine and Xenopus laevis, which caused the arginine to cysteine substitution at the X position in triple helix repeat region Gly-X-Y, affecting the function of fibrous protein and becoming pathogenic. Conclusions:Variant c.1693C>T p.Arg565Cys in COL2A1 gene is disease-causing in this family and this is the first report about the variant in China.