Genetic Diseases in the Horse
| Disease | Mode of Inheritance | Symptoms |
| Diseases with DNA tests | ||
| Glycogen Branching enzyme deficiency (GBED) | Autosomal recessive | Abortions, stillbirths or weak foals that die or have to be euthanized because of a metabolic disorder (Quarterhorse) |
| Overo Lethal White Syndome (OLWS) | Autosomal recessive | Foals cannot pass feced (Paint, carriers found rarely in miniature horses, half Arabians, TB, QH with overo white color pattern) |
| Hyperkalemic periodic paralysis (HYPP) | Autosomal dominant | Muscular disorder characterized by uncontrollable muscle twitching, paralysis, collapse or death (QH, appendix QH) |
| Severe combined immunodeficiency (SCID) | Autosomal recessive | Affected foals can't produce immune responses sufficient for protection against infections and rarely live longer than 5 months (Arabians) |
| Junctionsl epidermolysis bullosa (JEB) | Autosomal recessive | Foals have skin lesions over pressure points. The condition is untreatable and foals die within 14 days (Belgian, American Cream draft, Brenton draft and Comtois draft. The disease in American Saddlebred is from a different mutation) |
| Suspected diseases | ||
| Polysaccharide storage myopathy (PSSM) | Autosomal dominant | Causes tying-up in QH, Paints, Appaloosas. Another form causes muscle soreness, weakness and tying-up in draft, draft crosses and warmbloods |
| Degenerative suspensory ligament desmitis (DSLD) | 8 chromosomal regions identified | chronic, untreatable connective tissue disease that causes pain and abnomalities (Peruvian Pasos, TB, QH, Standardbreds, Arabians, warmbloods, draft) |
| Recurrent exertional Rhabdomyolysis (RE) | Autosomal dominant expression influenced by management |
Tying-up in TB, Standaardbreds |
| Hyperelastosis cutis (HC) | Autosomal recessive | Deep layers of skin are weak and thin so that they separate and tear easily |
| Laryngeal hemiplegia (roaring) | ?? |
One-sided paralysis of the larynx so that the airway collapses during exercise |
| Colic induced intestinal injury | ?? |
Decreased reparative proteins in the intestine |
| Osteochondritis dissecans (OCD) | Joint cartilage disorder due to local hormone expression | |
