Multiplex detection of wild-type and mutated FII (G20210A) and FV (G1691A) using whole blood (2 μL) as the DNA source in PCR. Lanes 1 through 3, undigested multiplex PCR products using the described conditions for FII (lane 1 [32 cycles] and 3 [40 cycles]) and for FV (lane 2). Lanes 4 through 9, undigested and Mnl I and HindIII double-digested PCR product electrophoresis of a patient double heterozygote for FII and FV; undigested and digested factor FV fragment (lanes 4 and 5, respectively); undigested and digested FII fragment (lanes 6 and 7, respectively); undigested and digested FII and FV fragments obtained after multiplex PCR (lanes 8 and 9, respectively). Lanes 10 through 13, double-digested products obtained after multiplex PCR from a normal individual (lane 10), an FII and FV Leiden double heterozygote (lane 11), an FII heterozygote (lane 12), and an FV Leiden heterozygote (lane 13). Products were separated on a 2.5% agarose gel (per lane, 20 μL of the digestion mix is loaded). Marker is a 100-bp size marker (GIBCO BRL, Grand Island, NY). Relevant fragment sizes in basepairs are indicated.