Direct detection of deletion mutation (Ex17 + 1del-g) in plasminogen intron Q by RFLP analysis. Amplified PCR products of plasminogen exon 17/intron Q were digested with Sty I, electrophoresed in a 2% agarose gel, and visualized by ethidium bromide staining. The (uncut) mutant type PCR fragment has a size of 203 bp; the wild-type Sty I-digested PCR fragment has a size of 143 bp. −, no Sty I added to PCR product; +, Sty I added to PCR product. Lane M, 100-bp ladder; lane 1, healthy control; lane 2, mother of patients no. 3 and 4; lane 3, father of patients no. 3 and 4; lane 4, patient no. 4; lane 5, patient no. 3. The larger (mutant) allele is found after Sty I-digestion in patients no. 3 and 4 (lanes 4+ and 5+, heterozygous) and their father (lane 3+, heterozygous), but not in the healthy control and not in the mother of patients no. 3 and 4 (lanes 1+ and 2+).