Human MNK cDNA clones and a genomic subclone derived from a 40-kb YAC clone that includes Pgk1 have been used to position the murine homologue of Menkes disease (MNK, Mnk) immediately proximal to, and within 150-200 kb of, phosphoglycerate kinase (Pgk1) on the mouse X chromosome using interspecific backcross analysis and pulsed-field gel electrophoresis.