A base substitution, an 8bp frameshifting deletion and a single base deletion that restores the normal reading frame. The alteration replaces 11 amino acids with 8 novel residues prior to the restoration of the normal reading frame. The mutation is in an evolutionarily conserved N-terminal extension of the basic DNA-binding domain.
The sisA3 allele is complex, consisting of a base substitution, an 8-bp frameshifting deletion, and a single-base deletion that restores the normal reading frame. 11 amino acids are replaced with 8 novel amino acids.
Male adult escapers are occasionally seen. These males are fertile and have normal morphology.
