Familial cutaneous lupus erythematosus (CLE) in the German shorthaired pointer maps to CFA18, a canine orthologue to human CLE

A familial form of lupus, termed exfoliative cutaneous lupus erythematosus (ECLE) has been recognized for decades in German shorthaired pointer dogs (GSP). Previous studies were suggestive of autosomal recessive inheritance. The disease presents as a severe dermatitis with age of onset between 16 and 40 weeks, and mirrors cutaneous lupus erythematosus (CLE) in humans. Lameness and, in advanced cases, renal disease may be present. Most affected dogs are euthanized before reaching the age of 4 years. The diagnosis is made by clinical observations and microscopic examination of skin biopsies. In humans, many different forms of CLE exist and various genes and chromosomal locations have been implicated. The large number of potential candidate loci combined with often weak association prevented in depth screening of the dog population thus far. During the course of our studies, we developed a colony of dogs with ECLE as a model for human CLE and the genetic analysis of these dogs confirmed the autosomal recessive mode of inheritance of CLE in GSPs. Using canine patient material, we performed a genome-wide association study (GWAS) to identify the genomic region harboring the gene involved in the development of the disease in GSPs. We identified a SNP allele on canine chromosome 18 that segregated with the disease in the 267 dogs tested. The data generated should allow identification of the mutant gene responsible for this form of cutaneous lupus erythematosus in dogs and assist in the understanding of the development of similar disease in humans.