mei-9D4/mei-9A2 females show 24% X chromosome nondisjunction, compared to 0.33% in wild-type females. mei-9RT1/mei-9D4 females show a severe decrease in the level of crossing over along the left arm of chromosome 2 compared to wild type. mei-9D4/mei-9A2 larvae are hypersensitive to ultraviolet light and show intermediate sensitivity to nitrogen mustard.
Hemizygous male larvae are weakly sensitive to HN2 and less sensitive to MMS than hemizygous male mei-9D1, mei-9D2 or mei-9D3 larvae. Homozygous females produce diplo-X and nullo-X exceptions at roughly the same frequency.