Of the eleven females, seven were found to be heterozygotes for X-ALD, two were diagnosed with other peroxisomal disorders (one D-bifunctional protein deficiency and one unspecified), one was homozygous for an ABCD1 mutation due to isodisomy X and classified as affected with X-ALD, and one is pending. This evidence concerns the gene ABCD1 and peroxisomal disease.