L Locus (Long Hair)

Other Names: L locus, long hair trait, longhaired trait, short hair trait, shorthaired trait
Affected Genes: FGF5
Inheritance: Autosomal Recessive
Mutation: Point Mutation
Breed(s): All Breeds
View Coat Color Diagram

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Testing Summary

The L Locus (Long hair) trait test reliably determines if a dog has one of the following genotypes at the L locus:

Sh/Sh

This dog carries two copies of Sh which results in short hair. This dog will pass on Sh to 100% of its offspring.

Interpretation: Shorthaired
Sh/Lh

This dog carries one copy of the Sh and one copy of Lh which results in short hair. This dog will pass on Sh to 50% of its offspring and Lh to 50% of its offspring.

Interpretation: Shorthaired (carries longhaired)
Lh/Lh

This dog carries two copies of Lh which results in long hair. This dog will pass on Lh to 100% of its offspring.

Interpretation: Longhaired


Detailed Summary

The L Locus impacts canine hair length as a result of a DNA variant in the FGF5 gene that prevents FGF5 from functioning as a hair growth termination signal in the hair follicle.


Testing Tips

Genetic testing of the FGF5 gene will reliably determine whether a dog is a genetic Carrier of long hair. Long hair is inherited in an Autosomal Recessive fashion, meaning that two copies of the Lh variant are required to produce long hair. Dogs with two copies of the Lh variant of FGF5, therefore, have long hair due to the lack of the hair growth termination signal. Dogs with one copy of Lh or no copies of Lh will have short hair.


References

  • Cadieu E, Neff MW, Quignon P, Walsh K, Chase K, Parker HG, VonHoldt BM, Rhue A, Boyko A, Byers A, Wong A, Mosher DS, Elkahloun AG, Spady TC, Andre C, Lark KG, Cargill M, Bustamante CD, Wayne RK, Ostrander EA. Coat variation in the domestic dog is governed by variants in three genes. Science. 2009 Oct; 326(5949):150-3. [PubMed: 19713490]
  • Dierks C, Momke S, Philipp U, Distl O. Allelic heterogeneity of FGF5 mutations causes the long-hair phenotype in dogs. Anim Genet. 2013 Aug; 44(4):425-31. [PubMed: 23384345]
  • Housley DJ, Venta PJ. The long and short of it: evidence that FGF5 is a major determinant of canine ‘hair’-itability. Anim Genet. 2006 Aug; 37(4):309-15. [PubMed: 16879338]