OBJECTIVETo detect the mutations in exon 6 of ABCD1 gene encoding adrenoleukodystrophy protein(ALDP) in Chinese X-linked adrenoleukodystrophy (ALD MIM 300100) patients.

METHODSGenomic DNA from 14 unrelated patients and two patients' parents with X-linked ALD was extracted using standard procedures from the peripheral blood leukocytes. Polymerase chain reaction (PCR) and DNA direct sequencing were employed to analyze exon 6 of ABCD1 gene.

RESULTSThree mutations in exon 6 were identified in 3 of 14 patients. One mutation was 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 error. 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 mutation, so there should be another mutation in this patient.

CONCLUSIONFor the first time, mutations in ABCD1 are identified in Chinese ALD patients in the mainland of China. No major gene deletion or rearrangement is detected in exon 6. Despite many mutations having been identified in patients with these clinical phenotypes, the genotype-phenotype correlations have not been clarified, suggesting that other genetic or environmental factors may also be involved in determining phenotypic expression in ALD. Two carriers are also confirmed.