Gene angora as a modifier of the hairless gene in mouse

The interaction between mouse angora-Y (Fgf5go-Y) and hairless (hr) genes have been studied. Homozygous mutant gene Fgf5go-Y increases length of all hair types, while homozygotes for the h gene lose hair completely starting on day 14 after birth. We obtained mice with genotypes +/+ hr/hr F2, +/Fgf5go-Yhr/hr and Fgf5go-Y/Fgf5go-Yhr/hr. Both +/Fgf5go-Yhr/hr and +/+ hr/hr mice began to loose hair from their heads on day 14. This further extended on the whole body. On day 21 the mice were completely deprived of hair. Therefore a single dose of gene Fgf5go-Y does not modify alopecia in mice homozygous for hr. However in double homozygotes Fgf5go-Y/Fgf5go-Yhr/hr alopecia started 4 days later, namely on day 18. It usually finished 10–12 days after detection of first bald patches. On days 28–30 double homozygotes lose coat completely. Hair loss in double homozygous mice was 1.5-fold slower than in +/+ hr/hr mice. This resulted from a significant extension of anagen phase induced by a mutant homozygous gene Fgf5go-Y in morphogenesis of the hair follicle. The hr gene was expressed at the transmission phase from anagen to catagen. Our data shows that the angora gene is a modifier of the hairless gene and this results in a strong repression of alopecia progression in double homozygous mice compared to +/+ hr/hr animals.