48, XXYY syndrome associated tremor.

48, XXYY syndrome is a form of sex chromosome aneuploidy that affects between 1 in 18 000 to 1 in 40 000 males. It is not inherited and is diagnosed by karyotyping. It has similarities to 47, XXY Klinefelter's syndrome, with tall stature, micro-orchidism, hypergonadotropic hypogonadism and infertility in males. However, patients with 48, XXYY syndrome also commonly have dental problems, tremor, attention deficit disorder, learning difficulties, allergies and asthma. The tremor is typically reported as an intention tremor (in 71% of patients XXYY aged >20 years with 48), which becomes more common with age and worsens over time.