Determination of genetic basis for splice variant identified in HL141. Genomic DNA from nucleotide 1873 (intron 3) to nucleotide 2139 (intron 4) of sample HL141 was amplified by PCR, cloned into PCR TOPO II vector and sequenced. (A) Agarose gel picture showing the 266 bp amplified product. Lane 1, 100 bp DNA ladder (New England Biolabs, Ipswich, MA). Lanes 2–4, 266 bp product amplified from genomic DNA of sample HL141. Lane 5, PCR negative control with no template added. (B) Alignment of HL141 amplified DNA sequence with CYP2D6 WT sequence, GenBank accession number M33388.