Polycystic ovary syndrome (PCOS) is the most
common multifactorial disorder of the endocrine
The results of recent studies implied that VDR genetic variants may impact PCOS and IR in
women with PCOS (
VDR gene contains 14 exons and is mapped
on chromosome 12cen-q12. Several allelic variations
have been reported in the VDR gene such
as the following restriction fragment length polymorphisms:
FokI in exon 2 (C/T) (rs10735810),
BsmI in intron 8 (G/A) (rs1544410), ApaI in intron
8 (C/A) (rs7975232), Tru9I in intron 8 (G/A)
(rs757343) and TaqI in exon 9 (T/C) (rs731236).
TaqI based restriction fragment length polymorphism
is located at the 3' end of the VDR gene. The
function of the TaqI-specific hypervariable polymorphism
is unclear (
The findings of Ranjzad et al. (
This matched case-control study was approved by the Ethical Committee of Urmia University of Medical Sciences and was performed in Urmia University of Medical Sciences (Urmia, Iran).
Between April 2011 and June 2012, a total of 76 women aged 18-40 years (38 patients with PCOS and 38 healthy women as normal controls) participated in this study. Women with PCOS and controls were unrelated and matched for gender, age, ethnicity, height, weight, and geographical region. Women with PCOS were clinically examined in assisted reproductive technology (ART) Reproductive Center and Infertility Clinic by ART and infertility specialists. Familial and medical history, physical evaluations, and clinical tests were carried out by the same physicians for all participants.
All diagnosis was based on the finding of three or
more of the criteria proposed by the Rotterdam criteria
Women with PCOS and controls without taking
any medications known to influence the endocrinal
system, carbohydrate, lipid and calcium metabolism
for at least three months before entering the investigation
were studied. Women, both cases and controls,
with a history of any known cause of oligomenorrhea,
amenorrea, hyper-androgenism including non-classic
congenital adrenal hyperplasia, hyper-prolactinaemia
and other confounding factors such as diabetes,
Cushing’s syndrome, androgen-producing tumours,
pregnant or breast feeding females, thyroid dysfunction,
cases with vitamin D supplementation as well
as individuals taking medications that affect calcium
homeostasis such as corcicosteroids, anticonvulsants
were excluded from the study (
Before blood sampling, informed written consent
was taken from all participants. A 3-5 mL aliquot of peripheral blood was collected with ethylenediaminetetraacetic
tubes for isolation of genomic DNA by standard
salting out method (
Genotypes of VDR TaqI in exon 9 (T/C) (rs731236)
were determined using the PCR-RFLP method in
controls and patients with PCOS (
Electrophoresis of PCR products and digested fragments was carried out on 2.5% agarose gel, and presence or absence of fragments were visualized by the UV transilluminator. The frequencies of VDR TaqI gene variant were computed by direct counting regarding T and C alleles and TT, TC, and CC genotypes in normal controls and patients with PCOS.
The frequencies of alleles and genotypes in the tested patient group were compared with the control group by using a Χ2 test. The data were analyzed regarding their fitness to Hardy-Weinberg equilibrium (HWE). A minimum sample size of 36 patients in cases had a statistical power of about 70% (two-tailed, α=0.10). The SPSS ver. 16.0 software and Microsoft Office Excel 2007 were used to calculate the Χ2 value, the odds ratio (OR), and 95% confidence interval (CI) as well as analysis of independent t test for detection of differences between cases and controls regarding clinical characteristics. P value less than 0.05 was considered statistically significant.
The clinical characteristics of women with PCOS are summarized in table 1. The studied group consisted of 38 Iranian Azeri PCOS patients (age range: 18-36 years; mean ± SD age, 26.03 ± 4.98) and 38 healthy women (age range: 20-40 years; mean ± SD age, 27.18 ± 4.95) (p>0.05).
The clinical characteristics of PCOS women
|26.03 ± 4.98||27.18 ± 4.95|
|160.61 ± 6.69||162.37 ± 6.44|
|74.01 ± 12.50||68.80 ± 12.16|
|28.56 ± 3.65||26.04 ± 3.90|
Data presented as means ± SD. BMI, body mass index.
There was no significant difference between women with PCOS and controls regarding clinical characteristics such as height and weight (p>0.05). There was a significant difference between women with PCOS and controls with respect to BMI (kg/ m2) (p<0.05). Our cases had a normal report on their blood tests regarding total testostrone level. Percentage of hirsutism and obesity (BMI>27 kg/m2) in tested patients were about 100% and 61.53%, respectively. LH and follicle-stimulating hormone (FSH) levels were equal to 7.52 ± 4.02 (IU/l) and 5.36 ± 1.89 (mIU/ml) respectively. The LH/FSH ratio was 1.44 ± 0.62 in our tested PCOS patients.
Allelic and genotypic frequencies of VDR TaqI polymorphism in exon 9 (T/C) (rs731236) are shown in table 2. Statistical analysis showed that cases (Χ2=1.99, p=0.369) and controls (Χ2=1.29, p= 0.523) were in agreement with HWE. The allele frequencies of VDR TaqI polymorphism were 0.605 and 0.395 in cases, and 0.697 and 0.303 in controls regarding T and C alleles. Also, the genotypic frequencies of VDR TaqI were 16 (42.11), 14 (36.84), and 8 (21.05) in cases, and 17 (44.74), 19 (50), and 2 (5.26) in controls regarding TT, TC, and CC genotypes, respectively.
There was no difference in genotype and allele
frequencies between PCOS and controls (
Allelic and genotypic frequencies of VDR TaqI in exon 9 (T/C) (rs731236) in cases and controls
|VDR TaqI T/C||F (%F) cases||F (%F) controls||OR (95% CI)||Χ2||P value|
|16 (42.11)||17 (44.74)||0.89 (0.36-2.22)||0.05||0.816|
|14 (36.84)||19 (50)||0.58 (0.23-1.45)||1.33||0.247|
|8 (21.05)||2 (5.26)||4.8 (0.94-24.33)||4.14||0.041|
|46 (60.53)||53 (69.74)||0.66 (0.33-1.30)||1.41||0.233|
|30 (39.47)||23 (30.26)||1.50 (0.76-2.94)||1.41||0.233|
Detection of VDR TaqI genotypes (T/C) via PCR-RFLP in 7 samples.
Current understanding of the molecular actions of
vitamin D in the reproductivity of women and calcium
homeostasis prompted the design of the present
study. The goal of this investigation was to study
whether the VDR TaqI gene variant in exon 9 (T/C)
(rs731236) is related to onset of PCOS for the first
time in Iranian Azeri women. PCOS is knwon as a
syndrome and affects ovarian function. PCOS most
commonly occur during adolescence and characterized
by several different features including amenorrhoea,
oligomenorrhoea, infertility as well as other
metabolic problems in medical findings (
IR is in association with reproductive abnormalities
in PCOS women. IR is corralated with vitamin
D metabolism in PCOS (
Patients with PCOS show higher levels of LH than
constant and lower level of FSH as compared with
This report suggests that the CC genotype of VDR TaqI in exon 9 (rs731236) is associated with PCOS.