The callipyge phenomenon: evidence for unusual genetic inheritance.

N. E. Cockett, S. P. Jackson, G. D. Snowder, T. L. Shay, S. Berghmans, J. E. Beever, C. Carpenter, M. Georges

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


In 1983, a male lamb exhibiting a pronounced muscular hypertrophy, particularly noticeable in the hind quarters, was born into a commercial Dorset flock in Oklahoma. The ram was premonitorily called Solid Gold. He subsequently produced offspring expressing the unusual phenotype, which is referred to as callipyge (Greek: calli- beautiful + -pyge buttocks). Animals demonstrating the callipyge phenotype are all descendants of this founder ram. These animals produce leaner, higher yielding carcasses, but there is some concern with decreased tenderness of the loin. Genetic characterization of the locus has demonstrated a unique mode of inheritance termed polar overdominance, in which only heterozygous offspring inheriting the mutation from their sire express the phenotype. The three other genotypes are normal in appearance. Progeny data indicate that reactivation of the maternal callipyge allele occurs after passage through the male germ line, although this reactivation is not absolute. The callipyge gene has been mapped to the distal end of ovine chromosome 18.

Original languageEnglish
Pages (from-to)221-227
Number of pages7
JournalJournal of animal science
Volume77 Suppl 2
StatePublished - 1999


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