Long Hair/Fluffy (L Locus)
Affected Genes: FGF5
Inheritance: Autosomal Recessive
Variant(canFam6):
Lh1=chr32:37372096 C>A
Lh2=chr32:37352815 G>A
Lh3=chr32:37352841-37352856 16 bp deletion CTCACTTCGGTGTATT
Lh4=chr32:37352831-37352832 2 bp insertion GG
Lh5=chr32:37364202 A>T
General Information: The L Locus (Lh) (Long Hair/Fluffy) trait in dogs is influenced by mutations in the FGF5 gene, which affect the hair growth cycle by preventing the termination signal for hair growth. Dogs with two copies of the Lh variant have long hair due to the continuous growth of their hair follicles. This trait is inherited in an autosomal recessive manner, meaning that a dog must inherit two copies of the Lh variant (Lh/Lh) to exhibit long hair. Dogs with one or no copies of the Lh variant (Sh/Lh or Sh/Sh) will have short hair. The presence of long hair can vary significantly between breeds, with some breeds like Labradors always having short hair, while others like Poodles consistently have long hair. Breeds such as Dachshunds can have either coat type depending on their genetic makeup.
Gene / Testing Information: Genetic testing for the FGF5 gene is essential to determine a dog's carrier status for the L Locus (Lh) long hair trait . This testing identifies the presence of Lh variants, which are responsible for the long hair phenotype. Since the trait is autosomal recessive, a dog must inherit two Lh variants to have long hair. Dogs with one Lh variant (Sh/Lh) will not show the long hair phenotype but can pass the gene to their offspring. When two carriers (Sh/Lh) are bred, each puppy has a 25% chance of being long-haired (Lh/Lh), a 50% chance of being a carrier (Sh/Lh), and a 25% chance of being short-haired (Sh/Sh). This genetic information is crucial for breeders, especially in breeds where long hair does not meet the breed standard. By using reliable genetic testing, breeders can make informed decisions to avoid producing puppies with undesirable traits and ensure the health and conformity of their breeding lines.
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 326(5949):150-153.
Dierks C, Momke S, Philipp U, Distl O. Allelic heterogeneity of FGF5 mutations causes the long-hair phenotype in dogs. Anim Genet. 2013 44(4):425-431.
Housley DJ, Venta PJ. The long and short of it: evidence that FGF5 is a major determinant of canine ‘hair’-itability. Anim Genet. 2006 37(4):309-315.
