Pre-symptomatic molecular diagnosis of X-linked adrenoleukodystrophy in Chinese families

OBJECTIVE: To identify asymptomatic males with X-linked adrenoleukodystrophy (X-ALD) from Chinese pedigrees by molecular genetic testing. METHODS: Genomic DNA was extracted from peripheral blood of the asymptomatic individuals from X-ALD families, and fragments spanning the proband's mutation were amplified. PCR-RFLP, direct sequencing and denaturing high performance liquid chromatography (DHPLC) were used to detect the PCR products. RESULTS: Four asymptomatic male subjects from three Chinese X-ALD pedigrees were found to carry the same mutation with the probands. In Pedigree 1, by restriction analysis with endonuclease Eco47 I, the digestion pattern of the proband's elder brother (Subject 1) was same with the proband, which indicated that both carried the same mutation. In Pedigree 2 and Pedigree 3, the PCR products were analysed by DHPLC, and the patterns of elution peaks of the Subjects 2-4 and the heterozygous mothers were similar, which indicated the presence of sequence alterations in the ABCD1 gene. DNA sequencing of the corresponding PCR products confirmed the mutations. CONCLUSIONS: Molecular testing was an effective way to determine the genotype of family members of X-ALD before they develop any symptoms. Early and preferable pre-symptomatic identification of hemizygotes is of great benefit to affected individuals and their families.