Citrin缺陷导致的新生儿肝内胆汁淤积症临床和SLC25A13基因突变的研究

Studies on the clinical manifestation and SLC25A13 gene mutation of Chinese patients with neonatal intrahepatic cholestasis caused by citrin deficiency

目的探讨citrin缺陷导致的新生儿肝内胆汁淤积症（neonatal intrahepatic cholestasis caused by citrin deficiency，NICCD）患儿的临床表现、实验室检查特点、SLC25A13基因突变情况及预后。方法对26例NICCD患儿进行常规实验室检查、血氨基酸谱和酰基肉碱谱、尿有机酸和SLC25A13基因分析，并随访2年。结果NICCD患儿出生体重偏低，平均黄疸出现年龄29d。实验室检查改变包括肝功能异常、高胆红素血症、低蛋白血症、甲胎蛋白升高、凝血酶原时间延长及低血糖、高氨血症。串联质谱分析发现多数患儿有瓜氨酸等氨基酸特异性升高。尿气相色谱质谱有机酸分析有尿4-羟基苯乳酸和4-羟基苯丙酮酸升高。SL（725A13基因分析共发现12种致病突变，其中G386V，R467X，K453R，1192—1193del T为新突变。26例患儿的突变总检出率84．6％，851del 4、1638ins 23及IVS6＋5G〉A为热点突变，突变率分别占总突变的40．9％、20．5％和11.4％。26例NICCD患儿中5例（19．2％）预后不良，4例死亡，1例接受肝移植。NICCD患儿的基因型与临床表型相关性不明显。结论85ldel4、1638ins23及IVS6＋5G〉A突变为中国人SLC25A13基因的热点突变，部分NICCD患儿可能预后不良。

Objectives To investigate the clinical and laboratory features of neonatal intrahepatic chotestasis caused by citrin deficiency （NICCD） and to characterize the molecular basis and prognosis of this disease. Methods Twenty-six patients with NICCD were collected because of idiopathic intrahepatic cholestasis and jaundice. The diagnosis was made by routine laboratory data collection, tandem mass spectrometry （MS-MS） and gas chromatography mass spectrometry （GC MS） analyses. SLC25A13 gene mutation was analyzed by using polymerase chain reaction （PCR）, direct DNA sequencing and restriction fragment length polymorphism analyses. The patients were followed up for nearly 2 years. Results The NICCD patients showed low birth weight and the average onset of jaundice was 29 days. Laboratory data showed liver dysfunction, hyperbilirubinemia, hypoproteinemia, high levels of a-fetoprotein, prolonged prothrombin time, hypoglycemia and hyperammonemia. MS-MS analysis of the blood samples revealed specific elevation of citrulline, methionine, threonine, tyrosine and elevation of free carnitine, short-chain and long-chain acylcarnitines. GC-MS analysis of the urine samples showed elevated 4-hydroxyl phenyllactic acid and 4-hydroxyl phenylpyruvic acid. Twelve different mutations were identified, including 4 novel mutations, i. e. , G386V, R467X, K453R and l192-1193delT. Forty four mutated alleles were identified in the 52 alleles （84.6%）. Among them, 851de14, 1638ins23 and IVS6＋5G〉A mutations were the most frequent mutations, accounting for 40. 9 G, 20. 5 G and 11. 4 % of the the total alleles examined respectively. Five of the 26 patients have not been recovered, including 4 died and 1 accepted liver transplantation. No obvious relationship was found between the genotype and phenotype in NICCI）. Conclusion The 851de14, 1638ins23 and IVS6＋5G〉A mutations are the hot-spot mutations in Chinese NICCD patients. Some NICCD patients have poor prognosis.