Objective: To identify ABCD1 gene mutation in a Chinese family with three heterozygous female patients.
Methods: Four fragments covering the entire coding sequence of the ABCD1 gene from one of the female patients were amplified by reverse transcription-PCR. The PCR products were directly sequenced. The result of sequencing was confirmed by restriction enzyme digestion of PCR products from genomic DNA. Human ABCD1 gene and ALD protein were aligned with those of rat, monkey, mouse and cattle by Clustal X 1.83. Softwares of Motif Scan, TMpred and ESYpred3D were used to predict the effect of the mutation on the structure of the ALD protein.
Results: A novel missense mutation, CAC to CGC, was found at codon 283 of the ABCD1 gene from the patient, resulting in the replacement of histidine by arginine. This mutation abolished an Msl I site in the gene. Her son was free from this mutation. The mutated amino acid residue (283H) was highly conservative in evolution, and the mutation caused a dramatic change in the structure of the ALD protein.
Conclusion: Three female patients heterozygous for ABCD1 gene mutation were first reported in China, and a novel mutation, p.H283R, was identified in this X-ALD family.