Because I am concerned with comparative aspects of the X chromosome, I have tried to create a companion volume to McKusick's catalog of X-linked phenotypes in man, Mendelian Inheritance in Man (MIM), and the format is patterned on it. I have used the same numbering system and have attempted to integrate the entries into McKusick's system: Apparently true homologies are given the number assigned in McKusick's catalog (with a few exceptions noted below); probable or possible homologies are given different numbers, but attention is drawn to the fact that a homologous relation with a human locus or phenotype might exist. To minimize any conflict or potential confusion, loci that are apparently unknown in man have been given numbers that are, as yet, unassigned in MIM. These general statements cover most entries; separate comment is required for a few others.

In attempting to comply with the recommendations of Lalley and McKusick (1985) noted in the Introduction, I have fitted homologous loci known in the mouse and other species into the human nomenclature system where appropriate; for example, the mottled series in the mouse and the mutation at the homologous locus in the Syrian hamster appear under MENKES SYNDROME. In one instance, although the same number (30150) is used, the entry is named after the normal product of the locus (Alpha-galactosidase A) not the mutant phenotype (Angiokeratoma, diffuse). Finally, in several instances, where I believe the MIM entry heading gives an inadequate notion of the nature of the locus, I have changed it.