Neonatal cerebellar ataxia / Bandera's ataxia (GRM1-related) - Coton de Tulear / Havanese

What does this test assess?

This genetic test analyses the GRM1 c.2331_2332ins62bp insertion in the Coton de Tulear and Havanese. The condition is also known as neonatal cerebellar ataxia, Bandera's neonatal ataxia, Bandera's ataxia, BNAt and neonatal ataxia.

The GRM1 gene encodes metabotropic glutamate receptor 1, a receptor important for signalling in the cerebellum. The tested insertion disrupts the coding sequence. When two variant copies are present, a severe coordination disorder appears very early in life.

What does this condition mean?

Affected puppies have problems with balance, posture and purposeful movement. They may tremble, show head nodding, struggle to stand or walk, scoot on the belly, fall to the side and paddle their legs. The condition mainly affects cerebellar function, so the puppy may seem mentally alert but cannot move normally.

Inheritance and result

The trait is inherited as autosomal recessive. A dog with one copy is a carrier; a dog with two copies has the genetically affected result for this GRM1 variant.

• N/N means the dog does not carry the tested insertion.
• N/ins62 means the dog is a carrier and can pass the variant to offspring.
• ins62/ins62 means the dog has two copies of the insertion and is genetically affected.

Practical value of this test

This test helps breeders manage a serious neurological disorder in Coton de Tulear and Havanese lines. Because carriers can look healthy, appearance alone cannot prevent the variant from circulating in a breeding population.

• The result identifies whether a breeding dog is clear, carrier or genetically affected for the tested variant.
• Breeders can avoid carrier-to-carrier matings and prevent affected puppies.
• Carrier dogs can be used responsibly with a clear partner, preserving valuable lines.
• The test gives concrete information for purchase, sale, breeding advice and checking related dogs.