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Dwarfism (Friesian)
Test number: 8553
Gene: B4GALT7
Price: £ 48.00 (including VAT)
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The Disease |
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Dwarfism in Friesian horses is characterized by physeal growth retardation of limbs and ribs while the head and back appear normal. A striking feature of the condition is hyperextension of the fetlock joints of all limbs with varying severity. Flexor tendon laxity, which is often seen in newborn foals of all breeds, fails to recover in dwarf foals and instead tends to increase further during aging. As a consequence, these dwarf Friesians develop an abnormal gait in which the limbs undergo extreme outward rotation at the level of carpus and hocks. The ribcage is abnormal in most cases with thickened and S-shaped costochondral junctions, leading to an inward protrusion of the chest at the level of Th10-16. Mature dwarfs have a head of the same size as unaffected horses, a broader chest with narrowing at the costochondral junction, a disproportionally long back and abnormally short limbs. The abdomen has a weak and rounded appearance, and the musculature over the body is poorly developed. A nonsense mutation in B4GALT7 is concordant with dwarfism in Friesian horses, which has an autosomal recessive mode of inheritance.
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Trait of Inheritance |
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Autosomal recessive trait
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Inheritance : AUTOSOMAL
RECESSIVE
trait
Sire
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Dam
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Offspring
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clear
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clear
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100% clear
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clear
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carrier
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50% clear + 50%
carriers
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clear
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affected
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100% carriers
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carrier
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clear
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50% clear + 50%
carriers
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carrier
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carrier
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25% clear + 25% affected
+ 50% carriers
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carrier
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affected
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50% carriers + 50%
affected
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affected
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clear
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100% carriers
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affected
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carrier
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50% carriers + 50%
affected
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affected
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affected
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100% affected
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Clear
Genotype: N / N [ Homozygous normal ]
The horse is noncarrier of the mutant gene.
It is very unlikely that the horse will develop Dwarfism (Friesian). The horse will never pass the mutation to its offspring, and therefore it can be bred to any other horse.
Carrier
Genotype: N / B4GALT7 [ Heterozygous ]
The horse carries one copy of the mutant gene and one
copy of the normal gene.
It is very unlikely that the horse will develop Dwarfism (Friesian) but since it carries the mutant gene, it can pass it on to its offspring with the probability of 50%. Carriers should only be bred to clear horses. Avoid breeding carrier to carrier because 25% of their offspring is expected to be affected (see table above)
Affected
Genotype: B4GALT7 / B4GALT7 [ Homozygous mutant ]
The horse carries two copies of the mutant gene and
therefore it will pass the mutant gene to its entire offspring.
The horse is likely to develop Dwarfism (Friesian) and will pass the mutant gene to its entire offspring
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Sample Requirements |
Hair Sample from mane with roots (approx 30 hairs) or 1 ml whole blood in EDTA tube.
How to obtain a viable hair sample
Pull around 30 hairs from the mane of the horse with the roots (in faols hair from the tail maybe taken). Wrap the hairs around your finger or a comb, as close as possible to the skin to ensure you obtain the hair roots. Keep dry, put in a bag, label the bag with the horse name, test (s) required. Place in an envelope and send back to us together with the order form. Broken or cut off hair will not be accepted.
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Price
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£ 48.00 (including VAT)
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| See also: |
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