肾上腺脑白质营养不良患者ABCD1基因第6外显子突变的初步分析

目的 检测肾上腺脑白质营养不良(adrenoleukodystrophy，ALD)(MIM300100)患者编码ALD蛋白的ABCD1基因ATP-结合盒(ATP-binding cassette，ABC)超家族中D亚家族1]突变。方法 提取无亲缘关系的14例中国ALD患者及其中2例患者父母基因组DNA。聚合酶链反应(polymerase chainreaction，PCR)扩增ABCD1基因的第6外显子，以琼脂糖凝胶电泳鉴定PCR产物，PCR产物纯化后DNA直接测序。结果 证实3个患者的ABCD1基因第6外显子有突变，其中1例患者为5’末端上游第6个碱基C缺失(1489-6 del C)，推测该突变可能导致剪切错误；1例患者为错义突变1559T→A(L520Q)，这两例患者的母亲均为杂合突变。另1例患者为1548G→A(L516L)的同义突变。结论 首次报告了中国大陆ALD患者ABCD1基因突变．第6外显子无大片段缺失和重组突变。同一血缘族中可有不同的表型存在，提示是否有其它遗传或环境因素参与表型的表达。通过DNA测序方法亦证实其中2例患者之母为ABCD1基因的杂合子。

Preliminary analysis of mutations in X-linked adrenoleukodystrophy gene (ABCD1) in Chinese patients

Objective To detect the mutations in exon 6 of ABCD1 gene encoding adrenoleukodystrophy protein(ALDP) in Chinese X -linked adrenoleukodystrophy (ALD,MIM 300100) patie nts. Methods Genomic DNA from 14 unrelated patients and two pat ients' parents with X-linked ALD was extracted using standard procedures from t he peripheral blood leukocytes. Polymerase chain reaction (PCR) and DNA direct s equencing were employed to analyze exon 6 of ABCD1 gene. Results Three mutations in exon 6 were identified in 3 of 14 pa tients. One mutation wa s deleted 1 base pair at splice acceptor-site (1489-6 del C). It was not clear what the effect of this mutation is on the ALD protein, maybe induce splicing er ror. One missense mutation: T1559A(L520Q).These two patients' mothers were heterozygous. The third patient had a mutation: G1548A (L516 L), which is a known polymorphism. It was not a disease causing mu t ation, so there should be another mutation in this patient. Conclusion For the first time, mutations in ABCD1 are identifi ed in Chinese ALD pa tients in the mainland of China. No major gene deletion or rearrangement is det ected in exon 6. Despite many mutations having been identified in patients with these clinical phenotypes, the genotype-phenotype correlations have not been cl arified, suggesting that other genetic or environmental factors may also be invo lved in determining phenotypic expression in ALD. Two carriers are also confirme d.