Osteogenesis imperfecta (BMP1-related)

Gene: BMP1

Transmission: Autosomal, likely recessive

For an autosomal recessive genetic disease an animal must have two copies of the mutation in question to be at risk of developing the disease. Both parents of an affected animal must be carriers of at least one copy of the mutation. Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Substitution, BMP1 gene: c.637G>A, p.(Val213Met), exon5, Chr.B1.

Medical system: Skeletal

Breed: Domestic

Age of onset of symptoms: Within three months.

Osteogenesis imperfecta, sometimes called brittle bone disease, is a family of hereditary diseases seen in animals involving improper bone formation. A range of clinical presentations can occur involving multiple bone fractures that can be less severe to life threatening. A number of gene mutations can be the cause of osteogenesis imperfecta, all of which affect, either directly or indirectly, the structure or function of the collagen 1 molecule, the main filamentous structural protein found in cartilage and bone.

A three-month-old domestic cat in Japan was presented with multiple fractures. Long bones were not bowed, and bone density appeared normal on radiograms. A diagnosis of osteogenesis imperfecta was made. Molecular studies performed on the cat’s genomic DNA reveled a homozygous mutation within the BMP1 gene. The BMP1 gene codes for Bone morphogenic protein 1, an enzyme and growth factor involved in cartilage and bone development and specifically involved in the maturation of collagen 1 molecules. Recessive mutations in the BMP1 gene in humans are the cause of osteogenesis imperfecta type XIII. The parents of the affected cat were not available for studies, and a survey of 220 unrelated cats was unable to detect the mutation.

These findings, although of academic interest, should not be of general concern to cat breeders.