Table 1. Comorbidities in Klinefelter syndrome: prevalence and mortality.
| Incidence | Reference | Mortality | Reference | |
| % | (SMR*) | |||
| Gynecomastia | 38 | (2) | – | – |
| Breast cancer | 0.3 | (e7) | 29 | (e7) |
| Thrombosis | 4.7 | (5) | 8 | (4) |
| Pulmonary embolism | 2.3 | (5) | 6 | (4) |
| Metabolic syndrome | 44 | (14) | – | – |
| Type 2 diabetes | 10 | (14) | 6 | (4) |
| Osteopenia | 40 | (18) | – | – |
| Osteoporosis | 10 | (18) | – | – |
| Hip fracture | ? | – | 39 | (4) |
| Maldescended testes | 27 | (2) | – | – |
| Mediastinal tumors | 0.4 | (5) | – | – |
| Epilepsy | 5.5 | (5) | 7 | (4) |
| Mental retardation | 4.2 | (5) | – | – |
| Delayed verbal ‧development | 40 | (19) | – | – |
| Language disorder | 70 to 80 | (21) | – | – |
| Legasthenia | 50 to 70 | (21) | – | – |
| Learning difficulties | 75 | (19) | – | – |
*SMR: standardized mortality rate, i.e. actual vs. predicted deaths (4)