斑状角膜营养不良近亲结婚的家系中新的CHST6突变研究

Novel mutations of CHST6 in a family of marriage between first cousins with macular corneal dystrophy

目的了解斑状角膜营养不良近亲婚配家系遗传结构特征,探讨斑状角膜营养不良临床表现、与CHST6基因突变的关系以及基因突变的类型。方法该斑状角膜营养不良的家系所有成员都经过详细病史询问、严格的眼科检查,留存外眼像。患者术中切除的病变角膜标本行组织病理学检查,采用标准方法行HE染色,采集7名成员外周血各5 mL,提取RNA,逆转录生成cDNA,对其产物测序,CHST6测序结果与正常人群进行比对。结果基因测序结果显示Ⅱ1和Ⅱ4的基因型为隐性纯合子。组织病理学检查发现先证者角膜基质中有大量的淀粉样物质沉积。斑状角膜营养不良家系中2例患者在两条等位CHST6基因上存在相同的点突变(1072T>C),余表型正常且与先证者有血缘关系的人员均是该突变基因的携带者。结论 2例患者的两条等位CHST6基因上存在相同点突变(1072T>C),基因型为隐性纯合子。

Objective To understand the genetic structure characteristics and investigate the relationship between gene mutations and clinical manifestations in a Chinese family characterized by consanguineous marriage with macular corneal dystrophy（MCD）.Methods Whole family was gathered to inquire about medical history in detail,and ophthalmology examinations were carefully and thoroughly carried on,including examination of visual acuity,slit-lamp biomicroscope,fluorescein staining,gonioscope.After carefully and comprehensively assessment,suggested the proband to have the focal excision and amniotic membrane transplantation.The impaired cornea was sent to histopathology department to analyze,the hematoxylin and eosin（HE） staining in the standard procedure was performed.Genomic DNA was extracted from peripheral blood of seven family members to conduct DNA sequencing.The observed nucleotide sequences were then compared with the published cDNA sequence of CHST6（NM_021615）.Results Histopathologists found abnormal deposits of glycosaminoglycans in stromal layer after performed HE staining.The same point mutations（1072T 〉C） was identified within the coding region of CHST6 on two alleles in two sufferers.All the other members with normal phenotype they had blood relationship with proband were heterozygotes carrying a point mutation 1072 T〉 C in CHST6 within one of alleles.Conclusion The same locus mutation of recessive gene homozygous（1072T〉 C） of CHST6 within two alleles exist in two suffers.