Hereditary cataracts in the John Rapp inbred strain of Dahl salt-sensitive rat.

Cataracts were apparently fixed in the genome of a highly inbred strain of Dahl salt-sensitive (S/JR) rat during the course of the selection for hypertension. Cataracts were present in S/JR rats inbred for more than 40 generations, but were not present in any of the salt-resistant rats (R/JR) inbred and observed during the same time. Light and electron microscopic evaluation of 11 pairs of S/JR rat lenses revealed a large posterior capsular defect and marked degenerative changes in lens fibers in each case. While the reason for the posterior capsular break is unclear, the cataract is probably a manifestation of an abnormal recessive gene or a recent autosomal dominant mutation.