Domestic cat SMA pedigree. Cats above the dashed line were privately owned, purebred Maine coon cats, and those below were purposely bred for this investigation. Squares indicate males, circles indicate females, filled symbols indicated cats exhibiting the SMA phenotype, and half-filled symbols indicate obligate carriers. All cats indicated by numbers were genotyped, but cat 80 and those numbered >229 were genotyped only during fine-mapping of the established disease interval. The investigational breeding colony was derived by gamete collection (semen from cat 58 and oocytes from the unrelated mongrel cat 180), in vitro fertilization, and embryo transfer.