Brachycephaly (skull shape) variant BMP3

Canine head shape ranges from elongated, dolichocephalic to markedly shortened, brachycephalic skull shapes. Genetic studies show that these differences are influenced by several genetic loci. In a genome-wide study, at least five regions were identified that contribute to variation in skull shape. One of these contains the BMP3 gene.

BMP3 belongs to the family of Bone Morphogenetic Proteins and plays a role in the regulation of bone development. The genetic variant results in an amino acid substitution in the BMP3 protein and has been identified particularly in small, strongly brachycephalic dog breeds. It may contribute to the development of a shortened, brachycephalic skull shape. Additional genetic factors, including variants in the SMOC2 gene, also influence facial length and skull shape.

It is important to note that the genetic test assesses the genetic influence on skull shape and does not directly determine disease risk. In simplified terms, the relationship can be described as follows: the genetic variant may influence skull development and contribute to a shortened facial skeleton. A pronounced brachycephalic skull shape may in turn be associated with an increased risk of certain health problems.

Relevance for breeding

The BMP3 test may be particularly relevant for breeding decisions when different BMP3 genotypes occur within a population. The test result indicates whether the variant associated with a brachycephalic skull shape is present and can be considered together with the phenotypic assessment of functionally relevant traits such as muzzle length, nostril opening or breathing.

However, in some strongly brachycephalic breeds, the described variant is already very common or nearly fixed. In these populations, breeding animals differ little or not at all with regard to this genetic factor. The test therefore offers only limited scope for genetic differentiation between breeding animals.

Please note: Actual skull shape is influenced by several genes as well as other factors. The BMP3 genotype therefore provides no reliable prediction of an individual dog's muzzle length or the degree of brachycephaly. Likewise, the test result does not allow an individual risk of BOAS or other brachycephaly-associated disorders to be determined.

For a well-founded breeding decision, the genetic result should therefore always be considered together with the dog's actual phenotype and functional assessment.