The primary features are infertility and small, poorly functioning testicles. Often, symptoms may be subtle and many people do not realize they are affected. Sometimes, symptoms are more prominent and may include weaker muscles, greater height, poor coordination, less body hair, breast growth, and low libido. Often, these symptoms are noticed only at puberty. Prenatal An estimated 60% of fetuses with<unk>  end in miscarriage. Physical As babies and children, XXY males may have weaker muscles and reduced strength. As they grow older, they tend to become taller than average. They may have less muscle control and coordination than other boys of their age. L During puberty, the physical traits of the syndrome become more evident; because these boys do not produce as much testosterone as other boys, they have a less muscular body, less facial and body hair, and broader hips. As teens, XXY males may develop breast tissue and also have weaker bones, and a lower energy level than other males. By adulthood, XXY males look similar to males without the condition, although they are often taller. In adults, possible characteristics vary widely and include little to no sign of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue). Gynecomastia is present in about a third of affected individuals, a slightly higher percentage than in the XY population. About 10% of XXY males have gynecomastia noticeable enough that they may choose to have cosmetic surgery. Affected males are often infertile, or have reduced fertility. Advanced reproductive assistance is sometimes possible. An estimated 50% of males with<unk>  can produce sperm. The term "hypogonadism" in XXY symptoms is often misinterpreted to mean "small testicles", when it instead means decreased testicular hormone/endocrine function. Because of (primary) hypogonadism, individuals often have a low serum testosterone level, but high serum follicle-stimulating hormone and luteinizing hormone levels, hypergonadotropic hypogonadism. Despite this misunderstanding of the term, however, XXY men may also have microorchidism (i.e., small testicles). The testicles of affected males are usually less than 2 cm in length (and always shorter than 3.5 cm), 1 cm in width, and 4 ml in volume. XXY males are more likely than other men to have certain health problems, such as autoimmune disorders, breast cancer, venous thromboembolic disease, and osteoporosis. In contrast to these potentially increased risks, rare X-linked recessive conditions are thought to occur less frequently in XXY males than in XY males, since these conditions are transmitted by genes on the X chromosome, and people with two X chromosomes are typically only carriers rather than affected by these X-linked recessive conditions. Cognitive and developmental Some degree of language learning or reading impairment may be present, and neuropsychological testing often reveals deficits in executive functions, although these deficits can often be overcome through early intervention. Also, delays in motor development may occur, which can be addressed through occupational and physical therapies. XXY males may sit up, crawl, and walk later than other infants; they may also struggle in school, both academically and with sports. It is estimated that 10% of men with<unk>  are autistic.<unk>  males have lower verbal memory capacity, and moderate to grave defects in elaborating and processing complex thoughts and ideas. Additional abnormalities include impaired attention, reduced organizational and planning abilities, deficiencies in judgment (often presented as a tendency to interpret non-threatening stimuli as threatening), and dysfunctional decision processing. Compared to individuals with a normal number of chromosomes, males affected by<unk> 's syndrome display behavioral abnormalities. These are phenotypically displayed as higher level of anxiety and depression, and mood dysregulation. These neurocognitive abnormalities are most likely due to the presence of the extra X chromosome, as indicated by studies carried out on animal models carrying an extra X chromosome.
Klinefelter syndrome
XYY syndrome
Kallmann syndrome
Turner syndrome
Wilson–Turner syndrome
Angelman syndrome
Parsonage–Turner syndrome
XYYYY syndrome