One copy of Su(var)321unspecified strongly suppresses position effect variegation (PEV) at the w locus caused by In(1)wm4.
One copy of Su(var)321unspecified is unable to suppress the telomeric position effect (TPE) in stocks carrying a variegating P{hsp26-pt-T}39C-5 insertion at the telomere of the left arm of chromosome two.
Originally isolated as a dominant suppressor of the w+ gene on In(1)wm4.