A Novel Double Mutation in the ABCD1 Gene in a Patient with X-linked Adrenoleukodystrophy: Analysis of the Stability and Function of the Mutant ABCD1 Protein
We diagnosed an adrenomyeloneuropathy (AMN) patient with a double novel missense mutation, c.284C>A (p.A95D) and c.290A>T (p.H97L) in a single ABCD1 allele. In skin fibroblasts from the patient, no ABCD1 protein was detected by immunoblot analysis, and the C24:0 β-oxidation activity was decreased to a level at which the ABCD1 protein was absent. To determine the responsible gene mutation in the patient, we constructed three kinds of mutated ABCD1 gene expression vectors (c.284C>A, c.290A>T or c.284C>A/c.290A>T) and transfected them into CHO cells stably expressing GFP-SKL (CHO/GFP-SKL cells) or CADDS fibroblasts lacking the ABCD1 gene. ABCD1 (p.H97L) displayed the correct peroxisomal localization in CHO/GFP-SKL cells, but ABCD1 (p.A95D) and ABCD1 (p.A95D/p.H97L) were diffuse in the cytosol. Furthermore, ABCD1 (p.H97L) was detected by immunoblot analysis and restored the C24:0 β-oxidation activity in the CADDS fibroblasts, as the wild type ABCD1 did. On the other hand, ABCD1 (p.A95D) and ABCD1 (p.A95D/p.H97L) were not detected and the C24:0 β-oxidation activity was not restored. These results clearly show that c.284C>A is the responsible gene mutation, whereas c.290A>T is a novel polymorphism.
KeywordsHuman Skin Fibroblast Posterior Tibial Nerve Peroxisomal Membrane Lignoceric Acid Posterior Tibial Nerve Stimulation
This research was supported in part by a Grant-in-Aid for Intractable Diseases from the Ministry of Health, Labour and Welfare of Japan, and for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (20590054, 22590060, 23590072). Pacific Edit reviewed the manuscript prior to submission.