- Usually 47XXY (sometimes others)
- Most common cause of hypogonadism in males
- Often undiagnosed as subtle symptoms (diagnosis made post-mortem)
- Normal life expectancy
Lack of testosterone leads to osteoporotic fractures
Also increased risk of:
- testicular cancer
- Autoimmune disorders like SLE / diabetes
- Male breast cancer
Kleinfelter’s patients may still be able to father children using modern sperm extraction techniques.
Androgen replacement therapy is the mainstay of treatment.