Canine coat length - test of FGF5-gene variants

The coat appearance belongs clearly to the main morphologic distinctions among dogs of different breeds.

In some breeds, short coat and long coat is possible, like in collies, border collies, dachshunds, German shepherds and St. Bernards. In some breeds,long or short variant in inacceptable, like fluffy coat in Welsh Corgi.

Long coat phenotype is inherited in autosomal recesive trait. Long coated dogs have two FGF5 gene variants in both alleles (each from different parent). In case of mating two FGF5 carriers, toeretically, 25% long coated offspring will born. In some breeds long hair phenotype was not elucidated.

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Genomia tests 4 FGF5 gene variants (c.284G>T, c.556_571del16, c.559_560dupGG, c.578C>T (Diers et al. 2013)) that influence the length of coat.

Table of FGF5 gene variants (Dierks et al. 2013)

Gene variant FGF5	Protein variant	Breed
M1: c.284G>T	p.Cys95Phe	Many breeds
M2: g.8193T>A (Genomia does not test this variant)	Blocking of exonu 2 splicing	Afghan Hound
M3: c.556_571del16	p.Ala186ThrfsX69	Eurasier
M4: c.559_560dupGG	p.Arg188AlafsX73	Afghan Hound, Eurasier
M5: c.578C>T	p.Ala193Val	Akita, Siberian Husky, Samoyed

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Possible results:

• If the result is N/N - the dog does not carry any variant specific for long hair - the dog has short hair
• If the result is N/M1or N/M3 or N/M4 or N/M5 – the dog carries one copy of the gene variant - the dog is short-haired, but it can give birth to long-haired offspring, if suitably crossed.
• If the result is M1/M1 or M3/M3 or M4/M4 or M5/M5 – the dog carries two same variants in the FGF5 gene - the dog is long-haired
• If the result is M1/M3, M1/M4, M1/M5, M3/M4, M3/M5, M4/M5 – the dog is long haired (dog inherited each variant from different parent – compound heterozygote carries two different FGF5 gene variants)

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Hair quality

There are distinguished three main characteristic hair types of dogs:

• hair length - short/long - FGF5 gene variants
• presence/absence of curls - KRT71 gene variants (Genomia does not tests these variants)
• presence/absence of traits: distinct moustache and eyebrows, characteristic for rough coated dogs - RSPO2 gene variants

Reference:

Cadieu E, Neff M, Quignon P, Walsh K, Chase K, Parker HG, Vonholdt BM, Rhue A, Boyko A, Byers A, et al.: Coat variation in the domestic dog is governed by variants in three genes. 2009;326:150-153.

D. J. E. Housley, P. J. Venta: The long and the short of it: evidence that FGF5 is a major determinant of canine ‘hair'-itability, Animal Genetics, August 2006