X-linked vacuolar myopathies: two separate loci and refined genetic mapping.

X-linked vacuolar myopathies can be divided into two forms: one that is associated with cardiomyopathy and mental retardation (XVCM-MR) and a second form, termed X-linked myopathy with excessive autophagy (XMEA), that spares cardiac muscle and has no central nervous system involvement. In this article, we demonstrate linkage between XMEA and markers on chromosome Xq28 and assign the XMEA gene locus to the most telomeric 10.5 cM of chromosome X. We also show that XVCM-MR is not allelic to XMEA.