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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 4, July/August 2016
216
AFRICA
An intended replication study (Erasmus Rucphen family
study) was carried out involving 2 347 participants. Both
studies observed that the minor alleles of
rs7895833
(G allele)
and
rs1467568
(A allele) were associated with lower BMI and
a 13–18% decreased risk of obesity in two independent Dutch
populations.
17
In another study, the A allele of
rs7895833
was
associated with increased risk of obesity and hypertension in
Japanese men.
15
Recent studies investigated the association between SIRT1
SNPs (
rs7895833
,
rs7069102
,
rs144124002
and
rs2273773
) and
CAD in a Turkish population. While
rs7069102
,
rs2273773
and
rs144124002
were significantly associated with increased risk for
CAD, they found no association between
rs7895833
and CAD.
21,22
Shimoyama
et al.
reported that SIRT1
rs7069102
and
rs2273773
were associated with abnormal cholesterol metabolism
and coronary artery calcification, respectively, in Japanese
haemodialysis (HD) patients. The study also found that the A
allele frequency of SIRT1
rs7895833
and G allele frequency of
rs7069102
were significantly lower in HD patients compared to
controls, suggesting an impact on survival.
19
The allele frequencies of
rs7895833
and
rs1467568
show
ethnic variation, and this is a possible reason for differing disease
patterns among populations. The frequency of the
rs7895833
A allele was relatively low (0.29) in Japanese compared to
Dutch, Turkish and Caucasian subjects who had similar allele
frequencies (0.80, 0.85 and 0.80, respectively).
15,17,23
The A allele
of
rs1467568
(reported as the protective allele) showed marked
difference in frequency between European (0.25) and Japanese
(0.84) subjects.
23
Conclusion
Both SNP variant alleles occurred more frequently in SA Indians
than in SA blacks, but no difference was found between CAD
patients and controls. This study is limited by sample size and
a larger study may be required to fully assess the functional
significance of these polymorphisms.
P Ramkaran thanks the National Research Foundation (NRF) for a scholar-
ship and UKZN (College of Health Sciences) for funding this study.
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Table 4. Characteristics of black controls according to the
SIRT1 rs1467568
and
SIRT1 rs7895833
genotype
SIRT1 rs1467568
genotype
p-
value
SIRT1 rs7895833
genotype
p-
value
Wild type (AA) Variant (AG+GG)
Wild type (AA) Variant (AG+GG)
BMI (kg/m
2
)
25.53
±
0.54
27.13
±
1.20
ns
25.58
±
0.63
26.57
±
0.87
ns
Total cholesterol (mmol/l)
4.12
±
0.12
4.47
±
0.23
ns
4.30
±
0.13
4.14
±
0.18
ns
LDL (mmol/l)
2.62
±
0.10
3.02
±
0.22
ns
2.78
±
0.12
2.71
±
0.16
ns
HDL (mmol/l)
1.05
±
0.045
1.03
±
0.088
ns
1.08
±
0.05
0.99
±
0.06
ns
Triglycerides (mmol/l)
0.99
±
0.072
0.93
±
0.15
ns
0.98
±
0.08
0.96
±
0.11
ns
Fasting glucose (mmol/l)
4.80
±
0.084
4.90
±
0.11
ns
4.87
±
0.11
4.77
±
0.08
ns
Fasting insulin (
μ
lU/ml)
7.69
±
0.67
12.11
±
3.74
ns
9.21
±
1.73
8.59
±
1.10
ns
HBA
1c
(%)
5.83
±
0.062
5.79
±
0.082
ns
5.87
±
0.07
5.76
±
0.077
ns
hsCRP (mg/l)
6.64
±
1.86
5.82
±
1.23
ns
7.81
±
2.42
4.83
±
0.84
ns
BMI
=
body mass index, LDL
=
low-density lipoprotein, HDL
=
high-density lipoprotein, HBA
1c
=
glycated haemoglobin, hsCRP
=
high-sensitivity C-reactive protein,
IL-6
=
interleukin-6, ns
=
non-significant.