This X-linked mutation causes copper deficiency, and is an appropriate animal model for Menkes disease (J:617). Phenotypic manifestations in male hemizygotes resemble those of other mutations at this locus, especially brindled. However, clinical manifestations can be alleviated by treating hemizygotes with CuCl₂. Treated males live beyond the normal age limit of 15 days, and are capable of breeding, so that homozygous females can be produced. These animals resemble hemizygous males. They have nearly white coat color and curly whiskers, with ataxia and tonic seizures beginning about day 8 and loss of weight beginning about day 10. Death occurs about day 15 (J:23995). Copper administration to normal and afflicted males and to heterozygous females increases copper content of various organs, but does not affect activity of the copper-containing enzyme cytochrome c oxidase (J:12745).