Heterozygotes are WT and segregate WT and Sterile Dpys. Homozygous rib-2(qa4900) animals give homozygous F2 animals that can develop to the adult stage but exhibit abnormal phenotypes such as egg-laying defects, increased body width, and reduced activity in movement. While the F2 qa4900 homozygotes are fertile, the F3 qa4900 homozygous progeny stop developing during gastrulation and fail to develop normally. 511 bp deletion in the region of intron2 to exon 6 of the rib-2 gene (K01G5.6).