Related Experiment Video
Updated: May 31, 2026

Shifting Zebrafish Lethal Skeletal Mutant Penetrance by Progeny Testing
Published on: September 1, 2017
Lethal genetic disorder in Poll Merino/Merino sheep in Australia
M R Shariflou1, C M Wade, P A Windsor
1Faculty of Veterinary Science, University of Sydney, Sydney, Australia. mohammad.shariflou@sydney.edu.au
Objectives:
Characterise a lethal genetic disorder in Poll Merino/Merino sheep
Design:
Pathological description of a new congenital multisystem disorder in a commercial sheep flock, and analysis of breeding data collected each lambing season between 2004 and mid-lambing season 2010.
Procedure:
Necropsies were conducted on six affected lambs and the mode of inheritance of the disorder was determined by pedigree and segregation analyses.
Results:
The affected lambs were dwarfs with multiple defects in several organs, including skeleton, heart, liver and kidneys. The disorder has been named brachygnathia, cardiomegaly and renal hypoplasia syndrome (BCRHS). Segregation analysis suggests the disorder is transmitted as an autosomal trait with a recessive mode of inheritance. An annual incidence of the disorder in the discovery flock of up to 2.5% was recorded.
Conclusions:
As a lethal disorder, the occurrence of BCRHS raises potential ethical and economic concerns for Merino breeders. The development of a DNA test would be useful to investigate its distribution in the Australian wool-sheep population. As the disorder affects both the skeleton and several critical organs, including the heart, it may provide a potential animal model for investigating key developmental processes in humans and other animals.
Related Concept Videos
Lethal Alleles
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...
Cloning of Dolly the Sheep
Epistasis
Incomplete Dominance
Animal Mitochondrial Genetics
In-vitro Mutagenesis

