Tobacco and Public Health - TCSC Indonesia

Table 35.2 (continued) Gene map
Chromosome no. Gene Map location
12
Most of the allelic variants studied were at the loci shown in the gene map above,
because the same biological reasoning about the process of addiction generally and
smoking behaviour particularly, led to the specification of these pathways as important.
However, many of the genes studied have been looked at by only a few investigators, the
phenotypes again vary considerably or are not well defined, individual sample size and
characteristics are imperfect, and the models of genetic action are poorly specified. All
of these factors hamper pooling and interpretation (Walton et al. 2001).
Two examples from our own work may illustrate the difficulties of deciding whether
particular genes are important candidates or not.
Candidate genes—false start?
DRD4 11q23
5HT3A 11
5HT3B 11
13 5HT2A 13q14–q21
14
15 nAChRβ,α3,α5 15q24
nAChR α7 15q13–q14
16 NET1 16q12.2
17 5HTT 17q11.2
PNMT 17q21q22
18
19 CYP2A6 19q13.2
CYP2β6 19q13.2
20 nAChRα4 20q13.2–q13.3
ADRαD 20
21
22 CYP2D6 22q13.1
COMT 22p11.2
X MAOa,MAO6 Xp11.3
5HT2C Xq24
Y
MICHAEL MURPHY ET AL.
Catechol O Methyl Tranferese (COMT) is a plausible candidate gene for involvement
in smoking behaviour. It catalyses the inactivation of amine neurotransmitters such as
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