Heterozygotes are WT and segregate WT, MuvUnc (n1046 e66) and n1531 homozygotes whose phenotypes range from a few dead larva to sterile adults. The normal larval lethality of n1531/n1531 is suppressed by the maternal contribution of n1046. n1046 is semi-dominant.

Heterozygotes are mostly non-Muv (about 20% will be Muv because n1700 is semi-dominant) and non-Unc. Hets segregate Twitchers which die at various larval stages or as Vul adults, because of the maternal effect rescue of n1531 by n1700. The Twitchers will not give viable progeny. Hets also segregate DpyMuvs. The strain segregates males which will mate, though not very well.