Amino acid replacement: P278L.
Nucleotide substitution: C833T.
Adults carrying fz17A1.Act5C in a fz21 background have an average of 1.8 +/- 0.4 extra tarsal joints in the leg compared to wild type.
fz17A1.Act5C partially rescues the wing margin phenotype of fz21 fz2C1 double homozygous clones.