title: Klinefelter syndrome diagnosed by prenatal screening tests in high-risk groups.
abstract: OBJECTIVE
  Klinefelter syndrome is a chromosomal disorder present in 1 out of 400 to 1,000 male newborns in Western populations. Two-thirds of affected newborns show a karyotype of 47,XXY. Few studies have examined the incidence of Klinefelter syndrome in Korea. The aim of this study was to investigate the incidence of Klinefelter syndrome by use of prenatal screening tests.
  
  
  METHODS
  From January 2001 to December 2010, 18,049 pregnant women who had undergone a chromosomal study for fetal anomalies were included. For fetuses that were diagnosed as having Klinefelter syndrome, the patients' medical records were retrospectively reviewed. Both parents' ages, the reason for the chromosomal studies, and karyotypes were investigated.
  
  
  RESULTS
  We found that 22 of 18,049 (0.12%) fetuses were diagnosed with Klinefelter syndrome. The incidence of this disorder in male fetuses was 22 of 9,387 (0.23%). Also, 19 of the newborns (86.4%) showed a karyotype of 47,XXY; the other newborns showed karyotypes of 48,XXY,+21; 48,XXY,+12[12]/46,XY[54]; and 47,XXY[6]/45,X[1]/46,XY[95]. The mean age of the mothers was 36.1 years, and 2 women had a past history of a Down syndrome pregnancy. Nine mothers had a normal spontaneous delivery, 9 mothers underwent artificial abortion, and 2 fetuses were spontaneously aborted.
  
  
  CONCLUSIONS
  The incidence of Klinefelter syndrome as reported in this study is higher than in previous studies. Further studies with a broader population should be considered to confirm these results.
authors.affiliation: Department of Urology, Cheil General Hospital & Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea.
authors.forename: Dae Gi
authors.initials: DG
authors.lastname: Jo
authors.forename: Ju Tae
authors.initials: JT
authors.lastname: Seo
authors.forename: Joong Shik
authors.initials: JS
authors.lastname: Lee
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Park
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Kim
keywords: Karyotype; Klinefelter syndrome; Male infertility