Lethality occurs during third instar larval or pupal stages. Mutants exhibit visible disc abnormalities: discs are abnormal. Clones induced in wild type discs are of normal size and shape.
Since sktl is nested within an intron of insc, and the locus corresponds to that previously known as 'fam', all alleles previously ascribed to 'fam' are considered to be alleles of both sktl and insc until shown to be otherwise.