Data concerning the effects of increased body mass index (BMI) on
ovarian and pregnancy outcome are rich, but the results are rather
controversial. Regarding pharmacogenetics, gene polymorphisms of
hormonal receptor genes, such as Estrogen Receptor alpha (ESR1),
Estrogen Receptor beta (ESR2) and FSH receptor (FSHR) genes, are
associated with ovarian stimulation and pregnancy outcome and may
constitute a useful tool for ART experts for the prediction of this
outcome. The aim of this study is to track differences in the
distribution of gene polymorphisms among obese non-PCOS and non-obese
patients concerning three distinct genes which are involved in the
ovarian stimulation mechanism: PvuII polymorphism of ESR1 gene, RsaI
polymorphism of ESR2 gene and Ser680Asn variation of FSHR gene, using
restriction fragment length polymorphism analysis and real-time
polymerase chain reaction. A total of 151 normally ovulating female
patients underwent IVF or ICSI. Interestingly, the pregnancy rate in the
BMI >= 30 kg/m(2) group was higher in a statistically significant way
(40.9% versus 17.8%, p=0.023). The obese patients of this study were
in need of increased total FSH dose in order to achieve a satisfactory
oocyte number (p<0.001) and needed more days of stimulation (p=0.002),
but also presented lower basal FSH levels (p=0.032), which may explain,
to an extend, the better pregnancy outcome. Concerning the polymorphisms
of ESR1, ESR2 and FSHR genes, we did not observe differences in the
genotype distribution when we compared the obese non-PCOS population
with the non-obese population. Thus, obesity does not constitute an
additional indication to perform a genetic analysis before entering an
IVF/ICSI program