Animals heterozygous for yDp4 are Dpy non-Flu non-Unc. Animals which have lost yDp4 are FluUnc. Animals homozygous for yDp4 are dead (embryonic lethal). Low percentage of non-Dpy non-Unc progeny. These give a high percentage of Unc male self-progeny and are inferred to be yDp4 XO hermaphrodites.