title: Mortality in patients with Klinefelter syndrome in Britain: a cohort study.
abstract: BACKGROUND
  Klinefelter syndrome is characterized by hypogonadism and infertility, consequent on the presence of extra X chromosome(s). There is limited information about long-term mortality in this syndrome because there have been no large cohort studies.
  
  
  OBJECTIVE
  Our objective was to investigate mortality in men with Klinefelter syndrome.
  
  
  METHODS
  We obtained data about patients diagnosed with Klinefelter syndrome at almost all cytogenetics centers in Britain, as far back as records were available, and conducted a cohort study of their mortality, overall and by karyotype.
  
  
  METHODS
  We assessed 3518 patients diagnosed since 1959, followed to mid-2003.
  
  
  METHODS
  The outcome measure was standardized mortality ratio (SMR).
  
  
  RESULTS
  A total of 461 deaths occurred. There was significantly raised mortality overall [SMR, 1.5; 95% confidence interval (CI), 1.4-1.7] and from most major causes of death including cardiovascular disease (SMR, 1.3; 95% CI, 1.1-1.5), nervous system disease (SMR, 2.8; 95% CI, 1.6-4.6), and respiratory disease (SMR, 2.3; 95% CI, 1.8-2.9). Mortality was particularly raised from diabetes (SMR, 5.8; 95% CI, 3.4-9.3), epilepsy (SMR, 7.2; 95% CI, 3.1-14.1), pulmonary embolism (SMR, 5.7; 95% CI, 2.5-11.3), peripheral vascular disease (SMR, 7.9; 95% CI, 2.9-17.2), vascular insufficiency of the intestine (SMR, 12.3; 95% CI, 4.0-28.8), renal disease (SMR, 5.0; 95% CI, 2.0-10.3), and femoral fracture (SMR, 39.4; 95% CI, 4.8-142.3). Mortality from ischemic heart disease was significantly decreased (SMR, 0.7; 95% CI, 0.5-0.9).
  
  
  CONCLUSIONS
  Patients diagnosed with Klinefelter syndrome have raised mortality from several specific causes. This may reflect hormonal and genetic mechanisms.
authors.affiliation: Section of Epidemiology, Brookes Lawley Building, Institute of Cancer Research, Sutton, Surrey SM2 5NG, United Kingdom. anthony.swerdlow@icr.ac.uk
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Swerdlow
authors.forename: Craig D
authors.initials: CD
authors.lastname: Higgins
authors.forename: Minouk J
authors.initials: MJ
authors.lastname: Schoemaker
authors.forename: Alan F
authors.initials: AF
authors.lastname: Wright
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Jacobs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002423:Cause of Death; D015331:Cohort Studies; D006801:Humans; D007621:Karyotyping; D007713:Klinefelter Syndrome / Q000235:genetics / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009030:Mosaicism; D012730:Sex Chromosomes; D006113:United Kingdom / Q000453:epidemiology