Citrin 缺陷导致的新生儿肝内胆汁淤积症 SLC25A13 基因分析

SLC25A13 gene analysis in neonates with intrahepatic cholestasis caused by citrin deficiency

摘要:

目的：Citrin 缺陷导致的新生儿肝内胆汁淤积症（NICCD）是一种由SLC25A13基因突变引起的常染色体隐性遗传病，临床可表现为肝内胆汁淤积性黄疸、低出生体重、生长迟缓和低蛋白血症等。本研究通过DNA测序技术探讨中国NICCD患儿 SLC25A13 基因突变类型。方法：针对 SLC25A13 基因的 18 个外显子及其侧翼区碱基序列设计引物，应用 PCR 技术扩增目的片度。PCR 扩增、纯化后直接测序，确定其突变类型。IVS16ins3kb 突变则采用巢式 PCR 和 RT-PCR 进行检测。结果：发现7种SLC25A13基因突变类型，包括851del4、1638ins23、IVS16ins3kb、IVS6+5G>A、c.775C>T（p.Q259X)、c.1505C>T（p.P502L） 和 c.1311C>T（p.C437C）；并确认一种复合突变类型［1638ins23+IVS16ins3kb］。其中c.775C>T（p.Q259X）、c.1505C>T（p.P502L）和 c.1311C>T（p.C437C）为新发现的基因突变类型。在20例NICCD患儿中，6 例为 851del4 纯合突变，7 例为杂合突变，另有 7 例为单一突变类型的杂合子。突变类型以 851del4 为主，占所有突变类型64%；其次为 1638ins23、IVS16ins3kb 和 IVS6+5G>A（分别占15%、12% 和 6%）。结论：851del4突变在 NICCD 患儿中最为常见。

Abstract:

OBJECTIVE: Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) which resulted from mutation in SLC25A13 gene can present transient intrahepatic cholestasis, low birth weight, growth retardation, hypoproteinemia and so on. This study aimed to identify the mutation type of NICCD patients by DNA sequencing. METHODS: Twenty children diagnosed as NICCD were consented to enroll in this study. PCR assays were performed to amplify the eighteen exons and its flanking sequences of SLC25A13 gene, which were defined as the upstream and downstream 50 bp from starting and ending site of the exons. Then the PCR products were purified and followed by automated DNA sequencing. The IVS16ins3kb mutation was detected by nested PCR and RT-PCR. RESULTS: Seven genetic variations of SLC25A13, termed as 851del4, 1638ins23, IVS16ins3kb, IVS6+5G>A, c.775C>T (p.Q259X), c.1505C>T (p.P502L) and c.1311C>T (p.C437C), were identified in the subjects, of which c.775C>T (p.Q259X), c.1505C>T (p.P502L) and c.1311C>T (p.C437C) were reported for the first time in NICCD patients. And a compound mutation of ［1638ins23+IVS16ins3kb］ was also identified. In 20 patients with NICCD, 6 patients were 851del4 homozygotes, 7 patients were compound heterozygotes, and 7 patients were heterozygotes of single mutation. 851del4 was the major mutation type (64%), followed by 1638ins23 (15%), IVS16ins3kb (12%) and IVS6+5G>A (6%). CONCLUSIONS: 851del4 is the major mutation type in Chinese patients with NICCD.