Table 3.

Example ethnic population frequencies of CYP2A6 and CYP2D6 alleles with known in vivo enzyme activity. Frequencies compiled from different studies in the same ethnic population are only approximately comparable. Data from Aklillu et al. 1996, Gyamfi et al. 2005, Haberl et al. 2005, Ingelman-Sundberg 2005, Nakajima et al. 2002, Yoshida et al. 2003.

Allele	Enzyme activity	Population frequencies (%)
		Caucasian	Japanese
CYP2A6*1A/B	Normal	88.4	48.3
CYP2A6*2	None	2.3	0
CYP2A6*4	None	1.2	20.1
CYP2A6*5	None	0	0
CYP2A6*7	Reduced	0	6.5
CYP2A6*9	Reduced	5.2	21.3
CYP2A6*10	Reduced	0	1.1
CYP2A6*12	Reduced	3	0
		Caucasian	Asian	Ethiopian
CYP2D6*2xn	Increased	1-5	0-2	16.0
CYP2D6*4	None	12-21	1	1.2
CYP2D6*5	None	2-7	6	3.3
CYP2D6*10	Reduced	1-2	51	8.6
CYP2D6*17	Reduced	0	0	9.0