Term
| What is semilobar holoprosencephaly? |
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Definition
| Forebrain developmental issue, when the brain doesn't separate into hemispheres during early development |
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Term
| Post-mortem of a foal reveals a flattened brain, lack of olfactory bulbs, inconspicuous longitudinal cerebral fissure and caudate nuclei that are not fully distinct. What was this foal's issue? |
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Definition
| semilobar holoprosencephaly |
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Term
| What is thought to be the cause of semilobar prosencephaly? |
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Definition
interference with SHH transcription factors which are essential for the development of the ventral pattern of the neural plate
-can be caused by ingestion steroid alkaloid cyclopamineduring gestation, or genetically inherited |
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Term
| What are the clinical signs of holoprosencephly (HPE)? |
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Definition
electrolyte imbalances because the hypothalamus is responsible in part for osmoregulation/osmostats, thirst regulating mechanisms etc
Result: hypernatremia, hyperchloremia
Hyperactivity due to abnormal cerebral cortex
Chewing/jaw twitching & seizures due to malformation of the cortex |
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Term
| Why do horses with HPE not have difficulty with locomotion the way their human counterparts do? |
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Definition
| locomation in horses does not depend on the cerebrum to the same degree |
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Term
| How is lavender foal syndrome inherited? What breed does it most commonly effect? |
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Definition
autosomal recessive
Arabians (egyptian esp.) |
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Term
| What are the clinical symptoms of LFS? |
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Definition
Tetanic-like seizures
Paddling legs
Nystagmus
Exaggerated flexor reflexes
Diluted coat colour |
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Term
True or False
All carriers of LFS will show clinical signs |
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Definition
False
Heterozygous individuals will not |
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Term
| If it isn't possible to do a DNA test on an animal, how else might you test for LFS? |
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Definition
| Skin biopsy, and you're looking for melanosome accumulation surrounding the nucleus of melanocytes |
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Term
| What causes lavender foal syndrome? |
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Definition
A deletion mutation, causing a frameshift that produces a premature stop codon
Defective Myosin V is produced instead of Myosin Type II, so myosin filaments are not properly assembled, and actin-myosin interactions are nonfunctional |
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Term
| What gene is associated with LFS? |
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Definition
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