中文摘要：

目的研究1个中国家系中2例胱氨酸病患儿的临床表现和致病基因CTNS遗传突变。方法通过家系调查、病史采集和生化指标测定,分析胱氨酸病的遗传特点和临床表型。进行PCR扩增基因组DNA,直接测序分析2例患儿的CTNS基因的突变位点。结果该家系中2例患儿均确诊为胱氨酸病,临床表现为典型的肾小管功能障碍,包括糖尿、蛋白尿、氨基酸尿、酸中毒以及高磷酸盐尿导致低磷性佝偻病;病例1同时存在甲状腺功能减退症。该家系符合常染色体隐性遗传特点,CTNS基因检测证实2例患儿均存在致病性错义突变（c.969C〉G）,父母均携带该位点杂合突变。结论本研究分析2例遗传性胱氨酸病患儿临床特点和基因突变。基因检测有助于遗传性范可尼综合征患者明确病因,以提高对该病的认识和诊治。

英文摘要：

Objective To elucidate the inheritance,clinical characteristics and the CTNS gene mutation in two siblings with cystinosis from a Chinese family.Methods Family investigation,history collection and biological examination were performed.Using direct sequencing of the entire coding regions,we identified a single missense mutation in CTNS gene.Results Two patients were diagnosed as cystinosis with typical renal tubular dysfunction including glycosuria,proteinuria,aminoaciduria,defective urinary acidification,and phosphaturia.The first case also suffered from hypothyroidism since 7 years old.These two clinically affected individuals were homozygous for a single missense mutation in CTNS gene encoding the mutant polypeptide N323K,which had been previously reported.Two parents were first cousins and heterozygous for this pathogenic mutation in CTNS gene.Conclusion This study of mutant N323K in CTNS gene is reported domestically in Chinese patients,and is helpful to improve the cognition and management to cystinosis.