A new genetic variant of mdx mice: study of the phenotype.

Genetic selection in a colony of mdx mice (suffering from X-chromosome-linked muscular dystrophy) resulted in generation of their new genetic variant. In this new variant, the genetic, biochemical, and histological markers of muscular dystrophy are combined with signs of oculocutaneous albinism (skin and fur depigmentation), transillumination of the iris, sharply reduced pigmentation of the retinal epithelium, and increase of the eyeball refraction). Two sensorimotor tests (negative geotaxis and wire back down hanging) detected other phenotypical characteristics of albino mdx mice carrying, in addition to the mutation in the dystrophin gene exon 23 (intrinsic of the "classical" black mdx mice), an extra mutation responsible for pigmentation disorders. Slow geotaxis, despite longer wire back down hanging capacity, was regarded as aggravation of the neurological dysfunction in albino mdx mice in comparison with black mdx mice.