Two novel haplotypes of CYP2D6 gene in a Japanese population.

Two novel haplotypes of CYP2D6 were found in Japanese subjects. One haplotype of the human CYP2D6 gene, newly designated as CYP2D6(*)44 allele, had both a novel single nucleotide polymorphism (SNP) of 2950G>C in intron 6 donor splice junction and a known SNP (82C<T). The newly detected mutation was as follows: SNP, 030418Tsubuko001; GENE NAME, CYP2D6; ACCESSION NUMBER, M33388; LENGTH, 25 bases; 5'-CGGATGTGCAGCG/CTGAGCCCATCTG-3'. In addition, we found the other haplotype, newly designated as CYP2D6(*)21B allele, containing -1584C>G, -1235A>G, -740C>T, -678G>A, and a gene conversion with CYP2D7 gene in intron 1 associated with CYP2D6(*)21. Both CYP2D6(*)44 and CYP2D6(*)21B alleles would cause a splicing error or a frameshift with impaired drug metabolizing function mediated by CYP2D6.