NSDHL Frameshift Deletion in a Mixed Breed Dog with Progressive Epidermal Nevi

Identification of Genetic Risk Factors for Monogenic and Complex Canine Diseases

Advances in DNA sequencing and other technologies have greatly facilitated the identification of genetic risk factors for inherited diseases in dogs. We review recent technological developments based on selected examples from canine disease genetics. The identification of disease-causing variants in dogs with monogenic diseases may become a widely employed diagnostic approach in clinical veterinary medicine in the not-too-distant future. Diseases with complex modes of inheritance continue to pose challenges to researchers but have also become much more tangible than in the past. In addition to strategies for identifying genetic risk factors, we provide some thoughts on the interpretation of sequence variants that are largely inspired by developments in human clinical genetics.

Genetics of inherited skin disorders in dogs

Canine genodermatoses represent a broad spectrum of diseases with diverse phenotypes. Modern genetic technology including whole genome sequencing has expedited the identification of novel genes and greatly simplified the establishment of genetic diagnoses in such heterogeneous disorders. The precise genetic diagnosis of a heritable skin disorder is essential for the appropriate counselling of owners regarding the course of the disease, prognosis and implications for breeding. Understanding the underlying pathophysiology is a prerequisite to developing specific, targeted or individualized therapeutic approaches. This review aims to create a comprehensive overview of canine genodermatoses and their respective genetic aetiology known to date. Raising awareness of genodermatoses in dogs is important and this review may help clinicians to apply modern genetics in daily clinical practice, so that a precise diagnoses can be established in suspected genodermatoses.

Ichthyosis and hereditary cornification disorders in dogs

The stratum corneum (SC), the outermost layer of the epidermis, serves a crucial role in maintaining body hydration and protection from environmental insults. When the stratum corneum is injured or when the genetic blueprints are flawed, the body is at risk of dehydration, secondary infections and allergen sensitization. Advancements in veterinary dermatology have revealed a wide gamut of disease from relatively benign to lethal that specifically arise from flawed structural proteins, enzymes or lipids needed to create the corneocytes and lipid bilayers of the SC. Some conditions closely mimic their human counterparts while others are unique to the dog. This review will focus on forms of ichthyosis in the dog.

MIA3 Splice Defect in Cane Corso Dogs with Dental-Skeletal-Retinal Anomaly (DSRA)

We investigated a hereditary syndrome in Cane Corso dogs. Affected dogs developed dental-skeletal-retinal anomaly (DSRA), clinically characterized by brittle, discolored, translucent teeth, disproportionate growth and progressive retinal degeneration resulting in vision loss. Combined linkage and homozygosity mapping delineated a 5.8 Mb critical interval. The comparison of whole genome sequence data of an affected dog to 789 control genomes revealed a private homozygous splice region variant in the critical interval. It affected the MIA3 gene encoding the MIA SH3 domain ER export factor 3, which has an essential role in the export of collagen and other secreted proteins. The identified variant, XM_005640835.3:c.3822+3_3822+4del, leads to skipping of two exons from the wild type transcript, XM_005640835.3:r.3712_3822del. Genotypes at the variant were consistent with monogenic autosomal recessive mode of inheritance in a complete family and showed perfect genotype-phenotype association in 18 affected and 22 unaffected Cane Corso dogs. MIA3 variants had previously been shown to cause related phenotypes in humans and mice. Our data in dogs together with the existing functional knowledge of MIA3 variants in other mammalian species suggest the MIA3 splice defect and a near complete loss of gene function as causative molecular pathomechanism for the DSRA phenotype in the investigated dogs.