Phenotype: Ovine hereditary chondrodysplasia (spider lamb syndrome) is 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.
Mode of Inheritance: Autosomal recessive
Alleles: N = Normal/Unaffected, S = Spider lamb syndrome
Breeds appropriate for testing: Suffolk, Hampshire, Southdown, Shropshire, Oxford, and other breeds and crossbreeds derived from Suffolk stock in the US
Explanation of Results:
- Sheep with N/N genotype will not have spider lamb syndrome and cannot transmit this spider lamb syndrome variant to their offspring.
- Sheep with N/S genotype will not be affected by spider lamb syndrome, but are carriers. They will transmit this spider lamb syndrome variant to 50% of their offspring. Matings between two carriers result in a 25% chance of producing a lamb with spider lamb syndrome.
- Sheep with S/S genotype will have spider lamb syndrome, a semi-lethal disorder associated with skeletal deformities.