Insertion of P-element construct CaSpeR into the sn gene. Insertion site is at -667 to -660bp of the sn gene (coordinates according to Roiha et al., 1988, FBRf0048245), this is thought to be in the 5' non-coding region of sn.
The phenotype of snC75.4 is similar to null alleles of sn.
Reversion frequency of snC75.4 is increased in heterozygous females.
Reversion frequency of snC75.4 is increased in heterozygous females.