  We consider initial stage of the evolution of AM CVn type stars with white
dwarf donors, which is accompanied by thermonuclear explosions in the layer of
accreted He. It is shown that the accretion never results in detonation of He
and accretors in AM CVn stars finish their evolution as massive WDs. We found,
for the first time, that in the outbursts the synthesis of n-rich isotopes,
initiated by the ${\mathrm{^{22}{Ne}(\alpha,n)^{25}Mg}}$ reaction becomes
possible.
