Hereditary Equine Regional Dermal Asthenia (HERDA)
HERDA
Hereditary Equine Regional Dermal Asthenia (HERDA) is a genetic skin disorder characterized by excessively loose skin, severe lesions, and scarring on the back of affected horses. The lack of adhesion between the layers of skin is due to a mutation in a gene required for proper collagen formation. Collagen is an important protein for all connective tissues including skin. Symptoms are first observed around the age of two when the horse typically starts under saddle. Since other skin conditions can mimic the symptoms of HERDA, veterinarians can use this test to aid in skin condition diagnosis. There is no cure for the disease and permanent scars eventually prevent the horse from being ridden.
Reading Your Results
A. (CLEAR/NORMAL):
These horses have two copies of the normal gene and will neither develop Hereditary Equine Regional Dermal Asthenia Deficiency nor pass this mutation to their offspring.
B. (CARRIER/NOT AFFECTED):
These horses have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop Hereditary Equine Regional Dermal Asthenia and will, if bred, pass the mutation to 50% of its offspring, on average.
C. (AT RISK/AFFECTED):
These horses have two copies of the mutation associated with Hereditary Equine Regional Dermal Asthenia which typically results in excessively loose skin, severe lesions, and back scarring.
Additional Details
Inheritances
Autosomal Recessive
Affected gene
PPIB
Chromosome
Ch. 1
Mutation
c.115G>A; p.G39R
Publication:
Tryon RC, White SD, Bannasch DL. Homozygosity mapping approach identifies a missense mutation in equine cyclophilin B (PPIB) associated with HERDA in the American Quarter Horse. Genomics. 2007;90(1):93-102. [PubMed: 17498917].
