Underscoring the relevance of ACSL mutations to ALD phenotypes, we also describe our identification of a young boy with an undiagnosed leukodystrophy who harbors a mutation in SLC27a6, encoding a very-long-chain ACS with homology to Bgm and Dbb (Steinberg et al., 1999a,b, 2000). The gene discussed is ACSBG1; the disease is adrenoleukodystrophy.