Nemaline Myopathy (NM Dog)

Nemaline myopathy (NM) is a disorder of muscle formation. Affected puppies show the first symptoms at the age of 8 weeks, among them muscle wasting, weakness, muscle twitching and difficulty moving. Because of the reduced quality of life, affected dogs are usually euthanised before reaching their first year of life.

The disease occurs in the American Bulldog. The inheritance is autosomal recessive.

Symptoms

Muscle wasting
Weakness
Muscle twitching
Difficulty moving

General Information

Nemaline myopathy (NM) is a disorder of muscle formation.
The muscle fibre structure is not formed correctly, which leads to dysfunction of the muscle.
Typical of the disease are the thread-like (Greek nema) and rod-like structures that can be seen in a muscle biopsy.
The first symptoms appear at the age of 8 weeks; affected animals usually have to be euthanised before reaching their first year of life.

Breeds affected

American Bulldog

Test Information

This mutation test detects a change of a single base pair (g.52734272C>A) in the NEM gene.

This mutation was discovered by Generatio GmbH in cooperation with other scientists, who also developed the corresponding tests.

Genotype and Lab Report

Inheritance: autosomal recessive

→ The disease only occurs if both alleles of the gene are affected by the mutation (nm/nm). Dogs that have only one allele with the causative mutation (N/nm) are clinically healthy carriers.

Genotypes:

N/N = genetically normal

The dog has no predisposition for NM and therefore cannot pass it on to its offspring.

N/nm = a carrier

The dog is a clinically healthy carrier. The variation is passed on 50% to the offspring, which are then also carriers.

nm/nm = affected

The variation would be passed on 100% to the offspring, but breeding age is usually not reached.

Recommendations

Carrier animals can be bred to normal animals (N/nm x N/N). Before using the offspring in breeding, it should be tested whether they are normal or carriers.
Mating two carrier animals (N/nm x N/nm) should be avoided because there is a 25% chance that the offspring will be affected.
Affected animals (nm/nm) should be excluded from breeding.

Literature

Evans, J.M., Cox, M.L., Huska, J., Li, F., Gaitero, L., Guo, L.T., Casal, M.L., Granzier, H.L., Shelton, G.D. and Clark, L.A., 2016. Exome sequencing reveals a nebulin nonsense mutation in a dog model of nemaline myopathy.Mammalian Genome, pp.1-8. Pubmed reference: 27215641. DOI: 10.1007/s00335-016-9644-9.

Further information is available at: Online Mendelian Inheritance in Animals.