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Il serait en effet intéressant de tester beaucoup d'individus et aussi de vieilles lignées.
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Et de vérifier aussi quelles types de b mutation le chien serait porteur, il y a 3 mutations différentes bs (stop codon), bd (proline deletion) et bc (cysteine substitution), les 3 affectant la production d'eumélanine et donnant des chiens roux si bb. On peut ainsi tracer un peu mieux qui transmet quoi.
Le CLT "est dit être BB", car les BA utilisés ne serait pas porteur de b (ce qui serait à développer dans le détail) et car aucun CLT roux ne serait né (ce qui dans une population si inbreedée, notamment les CLT slovaques, prouverait cette affirmation). Maintenant dans le papier original qui décrit cette mutation on trouve un passage intéressant sur un BA (Grackle dans le texte) porteur de b (lui même noir et blanc car ayant aussi B) dont le plus proche ancêtre roux serait 6 générations en arrière:
"Historical perspective on the brown mutations. The German
Longhair and Large Munsterlander were considered a single
breed until 1909, at which time the breed divided, based on
brown versus black coat color. The breeders were disconcerted
that the brown German Longhair bred true for coat color, but
the black dogs occasionally had brown pups. It is not sur-
prising that the recessive brown could be maintained in black
dogs for many generations. Grackle, who carries one copy of
the proline deletion in TYRP1 (Table 3), was black and white,
and her closest brown German Longhair ancestor is six gen-
erations back. The Large Munsterlander, Cora, carries one
copy of the premature stop codon in TYRP1, and she has had
brown pups in the past.
Since more than a single DNA sequence variant associated
with brown was found in some breeds (Labrador Retriever,
Large Munsterlander, Brittany Spaniel, Field Spaniel, Aus-
tralian Shepherd, German Shorthaired Pointer, Vizsla, Pu-
delpointer, Gri€on, German Wirehaired Pointer), these
mutations likely arose prior to the time of breed registry ori-
gins in the late 1800s. Furthermore, these three mutations
occur in longhaired, shorthaired, and wirehaired breeds, a
®nding which further predates these breed origins to the 1600,
or 1700s (Schmutz 1992)." Source: 2002 Schmutz, S.M., Berryere, T.G., Goldfinch, A.D. : TYRP1 and MC1R genotypes and their effects on coat color in dogs Mammalian Genome 13:380-387, 2002. Pubmed reference: 12140685