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Background
Due to the genetic heterogeneity of many diseases, the Sanger sequencing technology is far from satisfying the needs of scientific research and clinical applications. The next-generation sequencing (NGS) technology is being widely used in relevant studies because of its lower cost and much higher throughput.
Objective
This study was to explore the feasibility of NGS technology for the detection of genetic cause of congenital cataract.
Methods
A Chinese congenital cataract pedigree was collected from Luoyang city in Medical Genetic Institute of Henan Province in January, 2013. The peripheral blood of 2 ml was obtained from each 3 patients with congenital cataract (Ⅱ2, Ⅲ3, Ⅲ4) and 3 subjects with normal phenotype (Ⅱ3, Ⅲ1, Ⅲ2) in this pedigree respectively using EDTA anticoagulant tube. The mutant gene of proband was detected by NGS, and the result was verified by Sanger sequencing. Sanger sequencing was employed to determine the mutation sites of other subjects in this pedigree and further to perform the prenatal diagnosis. The research followed the Declaration of Helsinki, and the protocol was approved by the Medical Ethics Committee of Henan Provincial People’s Hospital. Written informed consent was obtained from each subject prior to any medical examination.
Results
Total 5 patients were found in 14 family members of 4 generations in this pedigree, including 2 males and 3 females in generation of Ⅰ, Ⅱ, Ⅲ, and the other family members showed normal phenotype, which followed autosomal dominant inheritance pattern. NGS revealed that the proband occurred a heterozygous mutation of c. 682(p. S228P) in the exon 6 of CRYYB1 gene, and the outcome was further confirmed by Sanger sequencing. In addition, this heterozygous mutant gene was also found in other patients of this pedigree. However, the genotype of c. 682 in the exon 6 of CRYYB1 gene was T/T wild type in the subjects with normal phenotype in this pedigree. The genotype of CRYYB1 gene was T/T wild type in the fetus (Ⅳ1) by prenatal diagnosis.
Conclusions
NGS is a useful tool for the detection of mutant gene in congenital cataractous pedigree. The heterozygous mutation of c. 682T>C(p. S228P) in the exon 6 of CRYYB1 gene is the causative mutation in this pedigree. NGS combined with Sanger sequencing enables prenatal diagnosis of the disease.