Table 3

Interethnic differences in the frequency of the major variant alleles of CYP2D6

Allele	Mutation	Consequence	Allele Frequency
Allele	Mutation	Consequence	European Caucasian	Orientals	Black Africans	Ethiopians and Saudi Arabians
			%
2D6^*2xN	Gene duplication or multiduplication	Increased enzyme activity	1–5	0–2	2	10–16
2D6^*4	Defective splicing	Inactive enzyme	12–21	1	2	1–4
2D6^*5	Gene deletion	No enzyme	2–7	6	4	1–3
2D6^*10	Pro34Ser, Ser486Thr	Unstable enzyme	1–2	51	6	3–9
2D6^*17	Thr110Ile, Arg296Cys, Ser486Thr	Reduced affinity for substrates	0	N.D.	34	3–9

Modified from Ingelman-Sundberg et al. (1999).