In other species: pig , rabbit , domestic cat , horse

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 164160 (gene) , 614962 (trait)

Mendelian trait/disorder: no

Mode of inheritance: Multifactorial

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2016

Markers: Having conducted a case-control study involving 57 Labrador Retrievers affected with diabetes mellitus and 61 controls, Davison et al. (2017) reported that "There was no association between the presence of the POMC deletion mutation and DM in this population of Labrador retriever dogs", leading them to conclude that "This study adds to the existing scientific literature indicating that there is little evidence for a direct link between obesity and DM in dogs".

Molecular basis: Raffan et al. (2016) reported that "Sequencing of candidate genes for obesity in Labrador retriever dogs identified a 14 bp deletion in pro-opiomelanocortin (POMC) with an allele frequency of 12%. The deletion disrupts the β-MSH and β-endorphin coding sequences and is associated with body weight (per allele effect of 0.33 SD), adiposity, and greater food motivation. Among other dog breeds, the deletion was only found in the closely related flat-coat retriever (FCR), where it is similarly associated with body weight and food motivation"

Prevalence: Intriguingly, Raffan et al. (2016) reported that the frequency of the POMC deletion was 45% "in a group of 81 Labrador retrievers used as assistance dog breeding stock" compared with a frequency of around 12% in random samples of Labrador Retrievers. As the authors explain, "Temperament and ‘‘trainability’’ are the main drivers for selection of assistance dogs, and ‘‘positive reinforcement’’ with food reward is a mainstay of puppy training. We therefore hypothesize that dogs carrying the POMC deletion may be more likely to be selected as assistance dogs. The fact that the allelic frequency at this locus is significantly out of Hardy-Weinberg equilibrium in assistance dog breeding stock could be seen as support for the notion that selection has occurred at this locus."

Breed: Labrador Retriever.

Associated gene: