A NEW DOMINANT RETINAL DEGENERATION (RD4) ASSOCIATED WITH A CHROMOSOMAL INVERSION IN THE MOUSE

An autosomal dominant retinal degeneration, called Rd4, was found in a stock carrying the inversion In(4)56Rk, which was induced in a DBA/2J male. The inversion encompasses nearly all of Chromosome 4. It is hom ozygous lethal and in heterozygotes is always associated with retinal degeneration. In affected mice, the retinal outer nuclear and plexifor m layers bean to reduce at 10 days of age, showing total loss at 6 wee ks. The recordable electroretinograms (ERG) showed poorly at 3 to 6 we eks and were barely detected after 6 weeks of age. Retinal vessel atte nuation, pigment spots, and optic atrophy appeared in the fundus at 4 weeks of age. Rd4 has not recombined with the inversion in an outcross , suggesting that the Rd4 locus is located very close to or is disrupt ed by one of the breakpoints of the inversion, either near the centrom ere or near the telomere, A human homolog would be expected to be loca ted on human chromosomes Ip or 8q. (C) 1997 Academic Press.