Table 2 Frequencies of CYP2D6 alleles among Malay Malaysians

Normal-function allele

*1

48 (0.253)

1.0

Wild-type allele

*2

17 (0.089)

Contains an expression-decreasing variant, 2850 C > T, whose effect is offset by two distant enhancer variants

*39

3 (0.016)

Defined by two variants also present in *2, 1661G > C and 4180G > C

Decreased-function allele

*10

84 (0.442)

0.25

Prevalent in Asian populations

*41

15 (0.079)

0.5

Decreases the level of full-length transcripts

Loss-of-function allele

*4

6 (0.032)

0

CYP2D6 protein truncated by erroneous splicing and frameshifting; a common defective allele in Caucasians

*5

15 (0.079)

Whole-gene deletion

Uncertain functional significance

*43

1 (0.005)

Unknown

A decreased-function allele that has not yet received an official CPIC activity value

*71

1 (0.005)

May be a poor-metabolizer allele, through its adverse effect on the insertion of the CYP2D6 protein into the membranes of endoplasmic reticulum

TOTAL

190 (1)