Fatal intoxication cases: cytochrome P450 2D6 and 2C19 genotype distributions

Many commonly used pharmaceuticals, such as antidepressants and neuroleptics as well as some illegal drugs, are metabolised by the cytochrome P450 enzyme debrisoquine 4-hydroxylase (CYP2D6). Of Caucasians, 7-10% lack this enzyme, which can, upon administration of drugs in normal therapeutic doses, lead to adverse reactions and unexpected intoxication, leading in turn even to a fatal outcome in some cases. Individuals (n=242) who had died due to intoxication by pharmaceuticals were genotyped for CYP2D6 and CYP2C19 and compared with a reference group of 281 blood donors. A single nucleotide polymorphism (SNP) method was used to identify five CYP2D6 alleles: *1 (wt), *2, *3, *4 and *6. The allele *5, a complete gene deletion, was identified by a multiplex amplification of long DNA fragments. Four CYP2C19 alleles *1 (wt), *2, *3 and *4 were also identified by SNP analysis. The prevalence of the CYP2D6 poor metaboliser (PM) genotypes in individuals with fatal intoxication was lower (4.7%) than expected from the frequencies of these genotypes in the blood donors (8.5%). A significantly lower frequency P