PCR amplification of D2S44 (YNH24) alleles.

We have successfully amplified D2S44 (YNH24) alleles by a method for long-distance PCR using a special polymerase enhancer, Taq Extender PCR Additive. The alleles amplified from DNA samples of 58 Japanese subjects ranged from 0.42 to 3.5 kb and were 1.5 kb shorter than those detected by Southern blotting of Hinf I-digested genomic DNAs. Although alleles longer than 3 kb were barely visible by ethidium bromide staining, we were able to visualize them clearly with SYBR GREEN I NUCLEIC ACIC GEL STAIN. PCR amplification of D2S44 alleles is much simpler than their restriction fragment length polymorphism (RFLP) analysis; therefore, our procedure is well-suited for use in medicolegal practice. With minor modifications, the method described here should be applicable to other loci of variable number of tandem repeats (VNTRs) that have been analyzed by Southern blotting.