Abstract

The Inverdale gene (FecX) is carried on the sheep X-chromosome. Males carrying the Inverdale gene always pass a copy to their daughters, but not to their sons. Females carrying a single copy will pass the gene on to half of their offspring (both male and female). Progeny testing to determine which rams carry the gene, and which offspring have inherited, is time-consuming. Successful management of the Inverdale gene will require a simple, quick inexpensive test to distinguish carriers and non-carriers. A research programme has been initiated to develop a DNA test using DNA markers which will identify carrier animals at birth. Our initial strategy to find suitable markers was to build a map of genes and DNA markers on the sheep X-chromosome as a framework for looking for the Inverdale gene. We have determined the relative positions of twenty genes and DNA markers on the X-chromosome by looking at the pattern of inheritance of the X-chromosome markers in sheep pedigrees established in flocks at Invermay and Tuatapere. We estimate that 80% of the chromosome has been eliminated in our search to the Inverdale gene. Efforts are now directed towards identifying the particular region of DNA in which the Inverdale gene might lie. Suitable markers must be close enough to the Inverdale gene to be always inherited with Inverdale. Once such markers are identified a test can be developed to determine the Inverdale status of animals. Adaptation of the current techniques will enable DNA to be isolated from a few drops of blood, a mouth swab, or the ear tissue from a newborn animal.

SM, Galloway, V Hanrahan, MP Potts, and DF Hill

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 307-309, 1995