H. Krausslich, ON THE GENETICS OF POINT AND BODY COLORS IN HORSES - IN COMPARISON TOMOLECULAR ANALYSES OF COLOR LOCI IN MICE, Zuchtungskunde, 68(1), 1996, pp. 1-11
SEARLE (1968) listed in ''Comparative Genetics of Coat Colour in Mamma
ls'' for horses the following polymorphic loci: A, B, C, D, E, G, R, S
(Z) and W. In mice the loci a, b, c, e and d have been identified, lo
calized and characterized on the molecular level. The consequences of
these results in mice on colour genetics in horses are discussed. The
conclusions of ADALSTEINSSON (1974), ANDERSSON and SANDBERG (1987), th
at chestnut/sorrel colours are caused by the recessive genotype at the
E-Locus rather than by the B-Locus are in good agreement with molecul
ar genetic results at the respective loci in mice. This good agreement
also holds true for allels at the A, B and E Loci which determine bla
ck colours as well. Blacks have the genotypes aa B-EE or aa B-Ee and j
et blacks--B-E(d)-. The correlations to Loci assumed to be responsible
for colour dilutions C, D and Z are also of interest. By comparative
mapping, the homologies between horses and other mammalian species can
be shown. It is concluded that identification, localization and chara
cterization of colour loci in horses is of great interest for horse br
eeding. Since experimental crosses in horses are too expensive, the in
formative families necessary for comparative mapping have to be establ
ished in herdbook populations. International standardized colour descr
iption systems and the complete registration of the colours of horses
are necessary for this pulpose. Since genetic defects and reduced resi
stance against diseases can be caused by pleiotropic effects of colour
genes, horse colour genetics is of economic and ethical importance.