Localization of the locus causing Spider Lamb Syndrome to the distal end of ovine Chromosome 6

Spider Lamb Syndrome (SLS) is a semi-lethal congenital disorder, causing se vere skeletal abnormalities in sheep. The syndrome has now been disseminate d into several sheep breeds in the United Stares, Canada, and Australia. Th e mode of inheritance for SLS is autosomal recessive, making the identifica tion and culling of carrier animals difficult due to their normal phenotype . Two large pedigrees segregating for the SLS mutation were established, an d a genome scan with genetic markers from previously published genome maps of cattle and sheep was used to map the locus causing SLS. Genetic linkage between SLS and several microsatellite markers, Oar-JMP8, McM214, OarJMP12, and BL1038, was detected, thereby mapping the SLS locus to the telomeric e nd of ovine Chromosome (Chr) 6. Alignment of ovine Chr 6 with its evolution ary ortholog, human Chr 4, revealed a positional candidate gene, fibroblast growth factor receptor 3 (FGFR3).