Feline GSD IV pedigree. Offspring of each mating are arranged on a horizontal line connecting vertical lines that descend from symbols indicating the parents. Squares indicate males, circles indicate females, filled symbols indicate GSD IV affected offspring, half-filled symbols indicate obligate carriers determined by breeding, and half-filled and open symbols indicate clinically normal cats. Numerals inside of symbols are the number of offspring, when greater than one, of the gender and clinical status indicated by the symbol, produced by that mating. All offspring were examined histologically or were observed clinically to adulthood. The colony founder cats, marked A and B, were a purebred NFC and an unrelated domestic shorthair cat, respectively. The cats labeled A, B, and C are the same cats so labeled in figure 7.