Susceptibility genes for bovine digital dermatitis found

By Joanna Lyford, Senior medwireNews Reporter

Researchers have identified genetic variants that influence susceptibility to bovine digital dermatitis (BDD), an infectious condition that causes lameness of the hindfoot.

The six single nucleotide polymorphisms (SNPs) identified in this study are candidates for future large-scale genetic studies of BDD, say Rachel Scholey (University of Manchester, UK) and co-authors writing in Veterinary Record.

BDD is an infectious disease that is known to be influenced by environmental factors, such as farm hygiene and housing conditions, and may also be linked to other non-healing hoof conditions.

There is wide variation in how individual cattle within a herd are affected, which has led to the hypothesis that when environmental conditions are suitable, host genetic factors may predispose individual animals to the disease.

To investigate, Scholey's team studied three commercial Holstein dairy herds endemic with BDD in England and Wales. Each herd was observed on five occasions in order to identify animals that were chronically severely affected or apparently unaffected by BDD.

In all, 23 BDD-susceptible cattle and 24 non-susceptible cattle underwent genotyping of 40,218 characterized SNPs. Six of these SNPs differed significantly between cases and controls, the researchers report.

The candidate SNPs included a gene located in intron 9-10 of the anaphase promoting complex subunit 4 (ANAPC4) on chromosome 6; it encodes a ubiquitin ligase essential for proteolysis of cell cycle regulators and for halting mitosis.

"Genetic variants impairing function in this gene, therefore, might be related to the excess skin cell proliferation seen in BDD lesions," write Scholey et al.

The other four SNPs were on chromosome 26 surrounding the gene HTRA serine peptidase 1 and included two within the gene itself (intron 1-2 and intron 3-4).

"In man, HTRA serine peptidase 1 has been implicated in diseases with inflammatory processes…; therefore, it could be related to the profound skin inflammatory response in BDD," the researchers remark.

They conclude: "This study presents a pipeline for larger future BDD genetic studies, when reducing costs of genome-wide typing and sequencing will allow thousands of samples to be processed.

"Given the implications of BDD on animal welfare, we feel such future studies will be of merit."

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