A Report of 7 Cases with Klinefelter's Syndrome Detected by Prenatal Screening Tests on Pregnant Women in a 4-Year Period (2006-2009), Tehran, Iran

Backgruond: Klinefelter’s syndrome (47،XXY) is a chromosomal abnormality in which the affected male babies have an extra X chromosome. It is also the most common abnormality related to sex chromosomes and is the second chromosomal abnormality after the Down syndrome. It''s prevalence is 1 in 500 to 1 in 1000 in different populations. According to reports، the risk of Klinefelter''s syndrome is increased with increasing maternal age just like other chromosomal abnormalities. This retrospective study was performed in Nilou Medical Laboratory (Tehran، Iran) during the years 2006-2009. According to many reports maternal biochemical markers used for Down''s screenings are influenced in other chromosomal abnormalities such as Klinefelter''s syndrome، too. The aim of this study was to determine: how many fetuses were affected with klinefelter''s syndrome and how this abnormality influenced on maternal biochemical markers'' pattern (in quad screening tests). For 29100 pregnant women (from 50 different cities) who referred to Nilou Medical Laboratory، the Quad screening test was performed and the risk for Down''s syndrome was calculated. Women with screening positive results، after their gestational age was confirmed by their physicians، were referred to genetic centers for amniocentesis. All those women were contacted 6 months later and asked about their pregnancy outcome and their baby gender and its health status. (out of 29100 babies born alive 14751 cases were boys and 14349 were girls). 7 babies out of 29100 had been diagnosed with Klinefelter’s syndrome (via amniocentesis). In those cases، maternal biochemical markers'' pattern was similar to the cases with Down syndrome (High hCG and inhibin A Moms، with low AFP and uE3 Moms). however; the decrease in AFP and uE3 Moms was not as much as with Down''s syndrome. Regarding to the official birth consensus statements during the years (2006-2009، the sex ratio obtained in this study (102/80) showed no significant difference with the sex ratio in the whole population (104/95). This study showed that in mothers with an affected fetus with Klinefelter''s syndrome the biochemical markers'' pattern was similar to those whose fetuses are involved with Down syndrome (High hCG and Inhibin A Moms while the AFP and uE3 Moms are slightly low or near normal value). Regarding to the Klinefelter''s syndrome prevalence (1 in 1000)، it was expected that 14. 7 babies (male) would have been involved with this syndrome، among which 7 babies were diagnosed through amniocentesis (after maternal screening tests performed)، So the detection rate of our tests for klinefelter''s syndrome was 47. 6%. This figure shows no significant difference with those reported by Schmit et al (41. 1%) in Germany. Besides; none of the 7 cases with Klinefelter''s syndrome، had abnormal findings in their prenatal sonography reports at all. This finding also correlates with those by De Viga C et al (Paris، 2001).