horse genetic diseases

Question 1

haemophilia

Answer 1

gene mutations on X gene, recessive; most males get is WW(white) and OO (ovaro white spotting), often in welsh (unable to clot)

Question 2

WFFS = warmblood fragile foal syndrome

Answer 2

common in warmblood, 2 copies of mutated LHI gene - cause defect in CT -> very extendable, thin, fragile skin -> severe lesions all over body; teating, ulceration

Question 3

LWO: lethal white ovaro

Answer 3

TC->AG mutation turns isoleucine to lysine in the protein “endothelin B receptor”, responsible for development of embryo, and limit precursor of melanocyte migration = white (n/o = carrier, oo=affected) similar to the human hirchsprung disease - lack of colon ganglions cause dilation of the colon: colic, foals die shortly after birth bc. intestinal blockage -> homozygous, no tratment -> death

Question 4

melanomatosis

Answer 4

common in most grey horse breeds. disorder of melanocyte migration cause benign melanomas, 15+ yrs. rounded black nodules around eyes, vagina, anus and skin

Question 5

HYPP

Answer 5

hyperkalaemic periodic paralysis caused by mis-sense point mutation, autosomal dominant. incr. potassium (K⁺) disturbe the sodium channels in skeletal muscle -> lameness, muscle twitch/paralysis/weakness. carrier shows no sign

Question 6

SCID

Answer 6

severe combined immunodeficiency is caused by a frameshift mutation caused by deletion in DNA-kinase genes of the SCID gene. Cause poor T/B lymphocyte function -> immunodeficiancy, death in young foals of arab horses. carriers get no symptoms.

Question 7

EPSM

Answer 7

equine polysccharide storage myopathy: exersice intolerance due to glycogen storage problems seen in quarter horse. Since carrier may develop symptoms, 75% can be affected of offspring of heterozytote parents

Question 8

HERDA

Answer 8

hereditary equine regonal dermal asthenia cause collagen defect where layers of skin is not held properly together, quarter horse

Question 9

GBED

Answer 9

glycogen Branching Enzyme Deficiency cause no glycogen storage in quarter and paint so the mucles and heart wont function leading to death (homozygous foals die within months), blood test to check DNA,