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Determination of the genetic cause of an internationally unique, naturally occurring muscular dystrophy in Western Australian Merino sheep

Supreme, Jez (2013) Determination of the genetic cause of an internationally unique, naturally occurring muscular dystrophy in Western Australian Merino sheep. Honours thesis, Murdoch University.

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Abstract

Muscular dystrophies (MDs) are neuromuscular disorders characterised by chronic, usually progressive, skeletal muscle weakness. Individuals often lose walking ability and can suffer terminal cardiorespiratory complications. Determining the genetics of a disease helps provide diagnosis, prognosis, genetic counselling, and the basis for rational therapeutic design.

A naturally occurring sheep model of autosomal recessive congenital MD was identified in WA in the 1950’s and preserved as a research colony. The pathological features and distribution of this MD is novel. A sheep model of MD is incredibly valuable; sheep have similar skeletal muscle mass to humans, representing a significant improvement over smaller mammals in which to trial therapies. Successfully characterising the causative gene(s) would enable a possible target for new therapies and may open new lines of investigation into better understanding and treatment of MD in humans.

This project utilised a two-pronged approach to investigate the genetics of this ovine MD. First, bioinformatics analysis of SNP genotyping for multiple individuals in the flock by a 50,000 SNP array in combination with the latest sheep genome reference build released by the International Sheep Genome Consortium, enabling homozygosity mapping, genetic linkage and association mapping. Second, molecular biological approaches further explored the identified prime candidate gene by cDNA sequencing.

This research project identified ROCK2 as the prime candidate gene most likely harbouring a mutation causing the muscular dystrophy in this internationally unique ovine model. It also demonstrated for the first time in sheep the existence of ROCK2m, an isoform of ROCK2 preferentially expressed in skeletal muscle. This work has set the stage for further investigations into ROCK2m and the ovine MD which will hopefully pinpoint the causative disease mutation.

Publication Type: Thesis (Honours)
Murdoch Affiliation: School of Veterinary and Life Sciences
Supervisor: Carter, K., Nowak, K., Laing, Nigel and Greene, Wayne
URI: http://researchrepository.murdoch.edu.au/id/eprint/20751
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