P{GT1} insertion in the third exon.
Hmt4-20BG00814 does not dominantly affect position effect variegation at the Sb locus which is caused by T(2;3)SbV.
Hmt4-20BG00814 suppresses the position effect variegation of the mutant Sb phenotype which is seen in the T(2;3)SbV chromosome.
Suv4-20BG00814 homozygotes suppress the variegation of Sb caused by T(2;3)SbV, resulting in an increase in the number of adults with a Sb mutant phenotype (short bristles).