Neuronal Ceroid Lipofuscinosis 7 / NCL7 (MFSD8-related) - Chihuahua / Chinese Crested

What does this test examine?

This genetic test analyses the MFSD8 c.843delT variant in Chihuahua and Chinese Crested dogs. The condition is known as neuronal ceroid lipofuscinosis 7, NCL7, CLN7, a Batten-like neurodegenerative disorder and MFSD8-related lysosomal storage disease.

MFSD8 encodes a lysosomal membrane/transport protein. The deletion causes a frameshift with an early stop codon, strongly truncating the protein and allowing storage material to accumulate in nervous tissue.

What does this condition mean?

NCL7 is a severe progressive neurodegenerative disorder. Affected dogs can develop blindness, anxiety, disorientation, compulsive behaviour, increased sleeping, sensitivity to stimuli, tremors, seizures and loss of coordination at a young age.

NCL disorders are lysosomal storage diseases in which nerve cells are gradually damaged. As a result, problems with vision, behaviour, coordination, movement and neurological function can increase over time.

Inheritance and result

The trait is inherited as autosomal recessive. Two copies of the variant cause the condition. Carriers have one copy, usually appear healthy, and can pass the variant on.

What does the result mean?

• Clear (N/N): the tested variant was not detected.
• Carrier (N/delT): the dog carries one copy and can pass the variant on.
• Affected (delT/delT): two copies cause MFSD8-related NCL7.

Practical value of this test

• Shows whether the dog is clear, carrier or genetically affected for the tested MFSD8 variant.
• Helps breeders avoid carrier-to-carrier matings and prevent puppies with a severe progressive neurological disorder.
• Provides valuable information before young, clinically normal or imported dogs are used for breeding.
• Supports line management when ataxia, behaviour change, vision loss, seizures or NCL occur in related animals.
• Makes communication with puppy buyers and fellow breeders more concrete because variant status is objectively known.

For breeders, this is especially useful because carriers can look healthy while two carriers together can produce affected puppies.