The gene for the gamma-subunit of retinal cGMP-phosphodiesterase is on mouse chromosome 11.

Mice carrying the rd mutation are affected with an autosomal recessive disease characterized by the total degeneration of retinal photoreceptor cells, which begins at postnatal day 8 and reaches completion by 3 wk of life. Biochemical studies have led to the proposal that a lesion in cGMP metabolism may be the cause of the rd photoreceptor degeneration, since cGMP reaches abnormally high levels in the rd retina a few days before the morphological pathology starts. The abnormal cGMP level is due to deficient cGMP-phosphodiesterase (cGMP-PDE) activity. A cDNA for the gamma-subunit of mouse cGMP-PDE has recently been cloned and characterized. We have mapped this cDNA to mouse chromosome 11 using a panel comprised of 19 hamster-mouse somatic cell hybrids by Southern blot hybridization. Our results suggest that the structural gene for the gamma-subunit of cGMP-PDE from mouse retina, which we have designated 'Pdeg', is not the primary defect in rd disease, as the locus of this genetic defect is on mouse chromosome 5.