Mitochondrial Fission Encephalopathy / MFE (MFF-related) - Bullmastiff

What does this test analyse?

This genetic test analyses the MFF c.471_475delinsCGCTCT variant in the Bullmastiff. The condition is named Mitochondrial Fission Encephalopathy, MFE, familial cerebellar ataxia with hydrocephalus and progressive neuronal abiotrophy.

MFF encodes mitochondrial fission factor, a protein involved in dividing and maintaining mitochondria in nerve cells. The frameshift variant disrupts this function and is linked to a severe progressive brain disorder.

What does this condition mean?

Affected Bullmastiffs often develop progressive coordination problems from a few months of age, including uncoordinated gait, abnormal behaviour, reduced vision, nystagmus and signs of hydrocephalus. The condition is severe, worsens over time and can lead to death or humane euthanasia within several months.

Inheritance and result

The trait is inherited as autosomal recessive. One copy makes a dog a carrier; two copies cause the genetically affected genotype.

Practical value of this test

• The test distinguishes clear dogs, carriers and dogs with the relevant genetic risk genotype.
• The result helps breeders plan matings deliberately and avoid risk pairings.
• Variant status can be documented clearly within lines, families and breeding advice.
• The test reveals carriers within a breed where the condition is severe and early-onset.
• For breeders, avoiding carrier-to-carrier pairings is especially important because affected puppies can develop a severe neurological disorder.
• The result supports transparent selection and helps prevent a rare but serious variant from circulating unnoticed in a line.

This test assesses the known MFF frameshift variant in Bullmastiffs. Other causes of ataxia, hydrocephalus or behaviour change fall outside this specific variant analysis.