One of the most common endocrine disorders in cats is diabetes mellitus (DM). DM is most commonly found in domestic shorthaired (DSH) cats along with Burmese cats also heavily represented in this population. The pathophysiology of DM in cats shares many characteristics with Type 2 DM in humans. Genome-wide association studies in people have located genes associated with DM and obesity. One of the genes identified, melanocortin 4 receptor (MC4R), plays a role in appetite regulation and energy balance.
The purpose of this study was to identify single nucleotide polymorphisms (SNPs) in the MC4R gene of the cats and whether these SNPs are associated with DM or overweight body condition in cats. Two hundred forty cats were enlisted for the study. Half of the group were diabetic cats (60 overweight, 60 lean) and the other 120 cats were non-diabetic controls (also 60 overweight, 60 lean). Ten cats had the coding region of the gene sequenced for SNPs. It was noted that a genetic factor (homozygosity of the MC4R:c.92C allele) may be associated with DM in overweight DSH cats. Because only 10 cats were ultimately evaluated by gene sequencing, there may be other less common SNPS present in MC4R in the cat. The authors feel that this genetic factor may influence susceptibility to DM in cats. The polymorphism may be involved in progression to overt DM in overweight cats, but it was not determined if this was a causal relationship or simply an association. The susceptibility may be more in line with a role in glycemic control in the presence of insulin resistance or the influence on pancreatic beta cell function in response to chronic hyperglycemia. [VT]