Genetic basis - caused by a single base-pair deletion in the EDA gene (NM_001014770.2:c.842delT) on the X chromosome. This deletion causes a frameshift mutation (p.Leu281HisfsTer22) resulting in a premature stop codon. EDA encodes ectodysplasin A, a protein essential for development of hair follicles, teeth, and sweat glands. The mutation leads to production of a truncated, non-functional protein, disrupting normal ectodermal development.
Pathophysiology - Ectodysplasin A deficiency results in hypoplasia or absence of hair, teeth, and sweat glands. Lack of sweat glands restricts thermoregulation and increases risk for overheating. Abnormal development affects skin appendages leading to hypotrichosis, dental abnormalities, and reduced gland function.
Complications - Increased susceptibility to overheating due to reduced sweat glands. Dental abnormalities that may require special care. Skin issues such as dryness or infections related to defective appendages. Affected males may have a reduced lifespan or require euthanasia due to severe symptoms.
Clinical Presentation - Mainly affects male puppies due to X-linked recessive inheritance. Symptoms include sparse or absent hair, missing or malformed teeth, and diminished sweat gland function. Carrier females may show mild or patchy hair loss but usually have normal dentition. Affected males exhibit more severe clinical signs and often have difficulty regulating body temperature.
Inheritance - X-linked recessive: males with the mutation on their single X chromosome are affected. Females must inherit two copies of the mutated gene to be affected, typically carriers with one mutated copy are asymptomatic or mildly affected. The mutation is usually inherited from a carrier dam.
Why This Matters to Breeders and Vets - Important for breeders to test for the EDA mutation to prevent producing affected male puppies. Veterinary awareness is critical to manage symptoms, including monitoring for overheating and ensuring dental health. Early detection aids in genetic counseling, breeding decisions, and supportive care to improve quality of life. Understanding genetic status reduces incidence and helps maintain healthier Dachshund populations.