Association of DLA-DQB1 alleles with exocrine pancreatic insufficiency in Pembroke Welsh Corgis

Exocrine pancreatic insufficiency (EPI) is a digestive disorder resulting from the insufficient secretion of enzymes from the pancreas. In dogs, this condition is often attributed to pancreatic acinar atrophy, wherein the enzyme-producing acinar cells are believed to be destroyed through an autoimmune process. Although EPI affects many diverse breeds, to date, molecular studies have been limited to the German Shepherd dog. A recent study of major histocompatibility genes in diseased and healthy German Shepherd dogs identified both risk and protective haplotypes. Herein, we genotyped DLA-DQB1 in Pembroke Welsh Corgis to determine whether dog leukocyte antigen alleles contribute to the pathogenesis of EPI across dog breeds. We evaluated 14 affected and 43 control Pembroke Welsh Corgis, which were selected based on an age of onset similar to German Shepherd dogs. We identified one protective allele (odds ratio = 0.13, P-value = 0.044) and one risk allele (odds ratio = 3.8, P-value = 0.047). As in German Shepherd dogs, the risk allele is a duplication of DLA-DQB1 (alleles DQB1*013:03 and 017:01); however, Pembroke Welsh Corgis have acquired a single polymorphism on DQB1*017:01. Thus, the DLA-DQB1 duplication is a risk allele for EPI in at least two breeds.

Characterization of the genetic basis for autosomal recessive hereditary nephropathy in the English Springer Spaniel

BACKGROUND

Autosomal recessive hereditary nephropathy (ARHN) was diagnosed in 2 English Springer Spaniels (ESS), a breed not previously reported to be affected by hereditary nephropathy (HN).

OBJECTIVE

To identify and characterize the genetic cause of ARHN in ESS.

ANIMALS

Sixty-three ESS (2 with ARHN, 2 obligate carriers, and 59 others), 2 mixed-breed dogs with X-linked HN, and 2 English Cocker Spaniels (ECS) with ARHN were included.

METHODS

ARHN was diagnosed based on transmission electron microscopy and immunostaining of kidney. DNA from affected dogs was screened for the mutation known to cause ARHN in ECS. Quantities of COL4A3, COL4A4, and COL4A5 mRNA transcripts in renal cortex were determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) for ARHN-affected dogs and 7 other dogs. The coding regions of COL4A3 and COL4A4 were sequenced for the 2 ARHN-affected ESS and an unaffected dog. Exon 30 of COL4A4 was sequenced for all 63 ESS.

RESULTS

qRT-PCR indicated a significant reduction in transcript levels of both COL4A3 and COL4A4 mRNA in the kidney of ARHN-affected ESS. Sequencing identified a single nucleotide substitution in COL4A4 at base 2806 resulting in a premature stop codon. Thirteen of 25 related dogs were identified as carriers.

CONCLUSIONS AND CLINICAL IMPORTANCE

A mutation highly likely to cause ARHN in ESS has been identified.