The loxP cassette in HCfs.w+ has been excised. The locus encodes H lacking introns and carrying a 7bp deletion between the second and third start codons. The mutation results in a frameshift and a premature stop codon in the p150 protein isoform. The p120 protein isoform can be produced. A residual attR site is present in the 5'UTR and a single loxP site is present in the 3'UTR.
Adult HCfs homozygous mutants display bristle defects with, on average, 11 (out of 40 present in wild-type) of the large head and thorax bristles affected; no abnormalities in wing venation are observed, but the wing size is significantly reduced compared to controls. However, when combined with the HattP allele, the transheterozygotes show very severe bristle defects (nearly all bristles affected).
H[+]/HCfs is a suppressor of visible | adult stage phenotype of DeltaB2
The wing notching phenotype of Df(1)N-54l9/+ heterozygotes is largely suppressed if they are also heterozygous for HCfs.
The vein thickening and vein deltas characteristic for HattP/+ adults is partially suppressible by combination with a single copy HCfs.