ABSTRACT
Repeated epilation (Er) is an autosomal dominant mutation that was probably radiation-induced (gamma rays on spermatogonia) as first reported by Hunsicker in 1960. It occurred in a random bred stock but was introduced, through several backcrosses, onto the C57BL/6J inbred background at the Jackson Laboratory then, later, onto the 129/Sv/Pas inbred background at the Institut Pasteur de Paris. Homozygous (ErlEr) mouse embryos can be recognized in utero as early as day 13.5, at which stage they start to exhibit abnormalities at the level of skin, tail, and limbs. Biochemical studies have shown that the histidine-rich, basic protein filaggrin, which is thought to embed tonofilaments in the normal cornified epidermal cell, forming a filament-matrix assembly, is absent from Er/Er mice and present in diminished amounts in Er/+ mice. Jones et al. demonstrated that liver retinoic acid and retinol are elevated 1.5 and 3.5 fold, respectively, in adult heterozygotes (Er/+) compared to normal (+/+) animals.
