Term
| What is the difference between genetics vs genomics? |
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Definition
Genetics = monogenic disorders
Genomics = polygenic disorders (mutations + normal physiology + evolution) |
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Term
What mode of inheritance does HYPP follow?
What chromosome & gene(s) is it associated with?
What type of mutation is it? |
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Definition
autosomal co-dominance
ECA 11 / SCN4A
missense (G is substituted for C) |
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Term
True or False
HYPP horses are sensitive to K+ |
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Definition
| true, extracellular K+ lowers the membrane excitation threshold of muscle cells |
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Term
| Describe the pathway followed/effect of potassium in HYPP patients |
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Definition
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Term
True or False
>50% of elite halter horses carry SCN4A allele |
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Definition
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Term
| What allele/gene mutation is associated with HYPP? |
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Definition
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Term
| How might you go about treating horses with HYPP? |
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Definition
Want to drive K+ into cells
-sugar entering cells also promotes K+ uptake, so giving glucose + insulin helps
-promote K+ excretion e.g. furosemide
-restrict K+ in diet |
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Term
What mode of inheritance does PSSM follow?
What chromosome & gene is it associated with? |
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Definition
autosomal dominant
ECA10 / GYS1 |
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Term
| What gene is associated with PSSM? |
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Definition
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Term
| What is the physiology behind PSSM Type 1? |
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Definition
| Sensitivity to insulin = very rapid cellular uptake of glucose & conversion to glycogen |
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Term
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Definition
| -rhabdomyelosis, muscle atrophy, muscle weakness esp. in hindquarters, muscle soreness etc |
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Term
| A biopsy indicates PAS positive polysaccharide inclusions within muscle tissue, what is the most likely issue? |
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Definition
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Term
| How do you treat & manage PSSM? |
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Definition
Treat: rest, fluids, NSAIDS, sedatives
Mangement: low CHO diet, supplemental fat in diet, lots of turnout & regular gentle exercise |
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Term
| Which type of PSSM can be genetically tested for? |
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Definition
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Term
| A thoroughbred with abnormal glycogen storage in muscle cells is most likely affected by (PSSM 1 / PSSM 2) |
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Definition
PSSM 2
(TBs, Arabs not typically affected by PSSM 1) |
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Term
What mode of inheritance does HERDA follow?
What chromosome / gene is associated? |
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Definition
autosomal recessive
ECA 1 / PPIB |
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Term
| What is the physiological problem occurring in horses with HERDA? |
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Definition
| thin collagen fibers within the dermal tissue = skin is fragile and excessively elastic |
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Term
True or False
Mares affected with HERDA are at high risk of mortality during foaling |
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Definition
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Term
| What is the developmental abnormality that leads to overo lethal white syndrome? |
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Definition
-in normal embryo development melanocytes & myenteric gangliocytes migrate from the neural crest to the skin & GI tract
-failure to migrate = white skin, dysfunctional peristalsis bc myenteric plexus is absent |
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Term
| The EDNRB gene is associated with what disease? |
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Definition
| ileocolonic aganglionosis (lethal white syndrome) |
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Term
| Genetic diseases are best managed.... |
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Definition
| proactively! test & evaluate before purchase/breeding! |
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Term
| What are some important management considerations when breeding animals at risk of genetic diseases? |
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Definition
Dominant traits SHOULD NOT BE BRED EVER.
Recessive traits with delayed onset may go unnoticed for a while (until offspring mature) - important to consider!
Recessive traits can possibly be bred out with careful management. Poor management will simply spread the undesireable allele more, making it difficult to avoid carrier-carrier matings in the future
Managing polygenic diseases (e.e. RAO/COPD, suspensory failure etc.) is very difficult |
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Term
| Brown swiss cattle are prone to... |
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Definition
weaver (bovine progressive degenerative myeloencephalopathy)
=progress loss of hindlimb coordination
Spinal dysmyelination
Spinal muscular atrophy |
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Term
| Jersey cattle are prone to... |
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Definition
limber leg = rotated shoulder & hip joints = can't stand
Rectovaginal constriction |
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Term
True or False
Scrapie in sheep is a genetic disease |
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Definition
| False! but susceptibility to it is genetically determined |
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Term
| What type of sheep are most resistant to scrapie? |
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Definition
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Term
| What type of sheep are most susceptible to scrapie? |
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Definition
| ARQ/ARQ, VRQ/ARK or VRQ/VRQ |
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