Rare chromosomal disorder that affects males, caused by the presence of an extra Y syndrome. Affected individuals are usually very tall, and may have experienced severe acne during adolescence. Other symptoms may include learning difficulties and behavioural problems.  It is estimated to occur approximately 1 in 1000 live births. May often be misdiagnosed.

Related conditions

Klinefelter syndrome, characterised by the presence in males of one or more extra X chromosomes. Common physical features include tall stature, delayed puberty, hypogonadism, and breast development.

Sotos syndrome. Variable genetic disorder characterised by excessive growth before and after birth, resulting in height and head circumference greater than average. Developmental delays affect most children with Sotos syndrome. Physical problems include scoliosis, seizures, hearing loss, congenital heart defects and kidney abnormalities.

Marfan syndrome. Genetic disorder affecting connective tissue throughout the body, including the heart and blood vessels. Symptoms include overgrowth of long bones of the arms and legs, scoliosis, and aortic aneurism or dissection.