Ovine hereditary chondrodysplasia (Spider Lamb Syndrome) is a semi-lethal inherited disorder associated with skeletal deformities in young sheep. Structural abnormalities observed in afflicted lambs include facial defects, humped or twisted spines, abnormally long legs, bent and/or splayed legs, flattened ribs, and an underdeveloped musculature. While the deformities may not be apparent at birth, they are often visible by 4-6 weeks of age. These combined musculoskeletal defects were first observed in black-faced lambs in the mid 1970’s.
Research into the cause of Spider Lamb Syndrome identified a mutation within the gene for fibroblast growth factor receptor 3 (FGFR3). Because the syndrome is a recessive genetic disorder, a lamb is only afflicted if both parents pass on the mutation. Thus, it is critical to identify carriers of the mutation. Carriers (animals with only one copy of the mutation) are structurally normal with no evidence of disease.
The VGL is licensed by Utah State University to perform testing of the FGFR3 mutation. Test results allow breeders to select appropriate breeding pairs to eliminate this condition from their herd.
Results are reported as :
|Test Result||Spider Lamb Syndrome|
|N/N||Animal does not have the FGFR3 mutation|
|N/S||Carrier, animal has one copy of the FGFR3 mutation – Breedings between carriers are expected to produce 25% affected lambs|
|S/S||Affected, animal has two copies of the FGFR3 mutation|
J. E. Beever, et al. (2006) A single-base change in the tyrosine kinase II domain of ovine FGFR3 causes hereditary chondrodysplasia in sheep. Animal Genetics 37: 66–71.