Breeds Affected: Labrador Retriever
Samples Accepted: Blood, Buccal Swabs
Disease Information: Centronuclear myopathy (CNM) is believed to be the most common hereditary disease affecting the muscle in Labrador Retrievers worldwide, with a carrier rate of up to 19% reported in the UK, 13% in the UA, and 11.4% in Canada (Maurer et al. 2012). The disease affects males and females equally, and symptoms include muscle wasting, weakness, irregular gait, and loss of patellar reflex.
Inheritance Information: CNM is autosomal recessive, meaning that animals with two copies of this allele will be affected. Animals with one copy of the gene will be clinically-normal carriers.
The possible genotypes are:
N/N The dog is normal, and cannot produce affected offspring.
N/cnm The dog is a carrier, and can pass the allele on to approximately 50% of any offspring. If bred to another N/cnm carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
cnm/cnm The dog is affected. If bred to a normal animal, 100% of the offspring will be carriers. If bred to an N/cnm carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/cnm x N/N) without any risk of producing affected offspring. The offspring should be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/cnm x N/cnm) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (cnm/cnm) should not be used for breeding.
Test Information: This mutation test identifies a SINE insertion in exon 2 of the PTPLA gene.
Pelé, M., Tiret, L., Kessler, J.L., Blot, S., Panthier, J.J.: SINE exonic insertion in the PTPLA gene leads to multiple splicing defects and segregates with the autosomal recessive centronuclear myopathy in dogs. Hum Mol Genet 14:1417-27, 2005. Pubmed reference: 15829503. Doi: 10.1093/hmg/ddi151.
Maurer, M., Mary, J., Guillaud, L., Fender, M., Pelé, M., Bilzer, T., Olby, N., Penderis, J., Shelton, G.D., Panthier, J.J., Thibaud, J.L., Barthélémy, I., Aubin-Houzelstein, G., Blot, S., Hitte, C., Tiret, L.: Centronuclear myopathy in Labrador retrievers: a recent founder mutation in the PTPLA gene has rapidly disseminated worldwide. PLoS One 7:e46408, 2012. Pubmed reference: 23071563. Doi: 10.1371/journal.pone.0046408.
Further information is available at the Online Mendelian Inheritance in Animals website.