Mutant for female meiotic segregation: 0.2% X chromosome exceptions from X/X females. 0% 4th chromosome exceptions from X/X females. 17.2% X chromosome exceptions from X/Bal females. 0% 4th chromosome exceptions from X/Bal females. Shows high levels of X nondisjunction but low levels of 4th chromosome nondisjunction. Primarily affects achiasmate chromosome segregation.
Excisions of P{lacW} lose the dominant meiotic phenotype.