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Abstract：
To analyse the genetic aetiology of a child with oculocutaneous albinism and to explore the effects of two mutation sites on the function of the OCA2 protein at the mRNA and protein levels via the use of recombinant carriers in vitro. Whole-exome sequencing (WES) and Sanger sequencing were used to analyse the pathogenic genes of the child and validate the mutations in the parents. pEGFP and phage vectors carrying wild-type and mutant OCA2 were constructed using the coding DNA sequence (CDS) of the whole gene-synthesized OCA2 as a template and transfected into HEK293T cells, after which expression analysis was performed. The child in this study was born with white skin, hair, eyelashes, and eyebrows and exhibited nystagmus. Genetic analysis indicated that the child carried two heterozygous mutations: c.1079C > T (p.Ser360Phe) of maternal origin and c.1095_1103delAGCACTGGC (p.Ala366_Ala368del) of paternal origin, conforming to an autosomal recessive inheritance pattern. In vitro analysis showed that the expression of the c.1079C > T (p.Ser360Phe) mutant did not significantly change at the mRNA level but did increase at the protein level, suggesting that the mutation may lead to enhanced protein stability, and the c.1095_1103delAGCACTGGC (p.Ala366_Ala368del) mutation resulted in the loss of three amino acids in exon 10, producing a truncated protein. In vitro expression analysis also revealed that the expression of the mutant gene was significantly downregulated at both the mRNA and protein levels, suggesting that the mutation can simultaneously produce truncated proteins and lead to protein degradation. This case study enriches the phenotypic spectrum of OCA2 gene disease. In vitro expression analysis confirmed that both mutations affect protein expression, providing a theoretical basis for analysing the pathogenicity of these two mutations.
摘要：
分析1例眼皮肤白化病患儿的遗传病因，并通过体外使用重组载体，从mRNA和蛋白水平探讨两个突变位点对OCA2蛋白功能的影响。使用全外显子组测序（WES）和Sanger测序来分析儿童的致病基因并验证父母的突变。以全基因合成的OCA2的编码DNA序列(CDS)为模板,构建携带野生型和突变型OCA2的pEGFP和噬菌体载体,转染HEK293T细胞,之后进行表达分析.这项研究中的孩子出生时皮肤白，头发,睫毛,和眉毛，表现出眼球震颤。遗传分析表明，该孩子携带两个杂合突变：c.1079C>T（p。Ser360Phe）的母体来源和c.1095_1103delAGCACTGGC（p。Ala366_Ala368del）的父系血统，符合常染色体隐性遗传模式.体外分析表明表达c.1079C>T（p。Ser360Phe）突变体在mRNA水平上没有显着变化，但在蛋白质水平上确实增加了，表明突变可能导致蛋白质稳定性增强，和c.1095_1103delAGCACTGGC（p。Ala366_Ala368del）突变导致外显子10中三个氨基酸丢失，产生截短的蛋白质。体外表达分析还显示，突变基因的表达在mRNA和蛋白质水平上都显著下调，表明突变可以同时产生截短的蛋白质并导致蛋白质降解。本病例研讨丰硕了OCA2基因病的表型谱。体外表达分析证实，两种突变都会影响蛋白质表达，这两种突变的致病性分析提供了理论依据。
