Signs and symptoms of Klinefelter syndrome vary widely among males with the disorder. Many boys with Klinefelter syndrome show few or only mild signs. The condition may go undiagnosed until adulthood or it may never be diagnosed. For others, the condition has a noticeable effect on growth or appearance. Signs and symptoms of Klinefelter syndrome also vary by age. Babies Signs and symptoms may include:  Weak muscles Slow motor development — taking longer than average to sit up, crawl and walk Delay in speaking Problems at birth, such as testicles that haven't descended into the scrotum  Boys and teenagers Signs and symptoms may include:  Taller than average stature Longer legs, shorter torso and broader hips compared with other boys Absent, delayed or incomplete puberty After puberty, less muscle and less facial and body hair compared with other teens Small, firm testicles Small penis Enlarged breast tissue (gynecomastia) Weak bones Low energy levels Tendency to be shy and sensitive Difficulty expressing thoughts and feelings or socializing Problems with reading, writing, spelling or math  Men Signs and symptoms may include:  Low sperm count or no sperm Small testicles and penis Low sex drive Taller than average height Weak bones Decreased facial and body hair Less muscular compared with other men Enlarged breast tissue Increased belly fat 
signs symptoms klinefelter syndrome vary widely males disorder  boys klinefelter syndrome show only mild signs  condition may undiagnosed adulthood may diagnosed  others  condition noticeable effect growth appearance  signs symptoms klinefelter syndrome vary age  babies signs symptoms may include:  weak muscles slow motor development — taking longer average sit up  crawl walk delay speaking problems birth  testicles haven't descended scrotum  boys teenagers signs symptoms may include:  taller average stature longer legs  shorter torso broader hips compared boys absent  delayed incomplete puberty puberty  muscle facial body hair compared teens small  firm testicles small penis enlarged breast tissue (gynecomastia) weak bones low energy levels tendency shy sensitive difficulty expressing thoughts feelings socializing problems reading  writing  spelling math  men signs symptoms may include:  low sperm count sperm small testicles penis low sex drive taller average height weak bones decreased facial body hair muscular compared men enlarged breast tissue increased belly fat 
klinefelter syndrome