Menkes X linked disease: two clonal cell populations in heterozygotes.

Abstract
The 64Cu incorporation into fibroblast clones obtained from 3 obligate and 3 suspected Menkes disease heterozygotes was studied. For each obligate heterozygote, 2 clonal cell populations were observed, 1 with a Menkes phenotype and 1 with a normal phenotype, as predicted by the Lyon hypothesis. The cloning results suggested a heterozygous state in 2 of the suspected carriers. The theoretical and practical limitations of the cloning method for identification of carriers of X-linked diseases are discussed.