Heterozygotes show no effect on crossing over between kni and pp.
Strongly semi-lethal in homozygous males, weakly semi-lethal in homozygous females. Homozygous females are sterile and do not produce any eggs. Homozygous males have a spread-wing phenotype, and strongly reduced fertility. Dominant suppressor of position effect variegation at the w locus caused by In(1)wm4h.