Centronuclear myopathy / CNM (HACD1/PTPLA-related) - Dog

About centronuclear myopathy

Centronuclear myopathy is an inherited neuromuscular disorder in Labrador Retrievers. It is also known as CNM, Type II Fiber Deficiency, Hereditary Myopathy of Labrador Retrievers or HMLR, and as autosomal recessive muscular dystrophy. These names refer to the same disease pattern in which skeletal muscle development and function are impaired.

Puppies often appear normal at birth, but muscle weakness, low muscle tone, exercise intolerance, an abnormal gait and progressive muscle wasting can develop at a young age. Signs may become more obvious during stress, exercise or cold conditions. In more severe cases, swallowing difficulties, aspiration or other complications can occur.

What does this test detect?

This DNA test detects the HACD1 variant c.203_204ins[N[236];CACACAAAGGTTT]. The gene was historically also referred to as PTPLA. The variant is a SINE insertion that disrupts normal gene processing and is consistent with HACD1/PTPLA-related CNM in Labrador Retrievers.

Inheritance and interpretation

CNM is inherited as an autosomal recessive trait. A dog with one copy is a carrier and is usually not clinically affected by this variant. A dog with two copies has a genotype consistent with risk for CNM/HMLR.

Practical value of this test

The result helps breeders identify carriers and avoid carrier-to-carrier matings. For veterinarians and owners, the test can provide useful genetic context in young Labradors with muscle weakness, exercise intolerance or neuromuscular signs. A clear result for this variant does not exclude other causes of muscle weakness.