ABCD1 and Klinefelter syndrome: Of the other two living non-ZSD cases, one case was diagnosed with Klinefelter syndrome (KS) and was found to have a hemizygous VUS variant in ABCD1, while the other non-ZSD case has a heterozygous 84 kb contiguous gene deletion on the long arm of the X chromosome including the ABCD1 gene, which was classified as a VUS.