Chromosome XYY syndrome. 47,XYY syndrome. Jacob syndrome.
Incidence
This condition occurs in about 1 in 1,000 newborns. Five to 10 children with 47,XYY syndrome are born in the United States each day. Many affected individuals are never diagnosed or not diagnosed until later in life. 47,XYY syndrome is not inherited. The chromosomal change occurs as a random event.
Clinical Characteristics
47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Affected children can have delayed development of motor skills (such as sitting and walking) or weak muscle tone (hypotonia). Other signs and symptoms of this condition include hand tremors or other involuntary movements (motor tics), seizures, and asthma. Individuals with 47,XYY syndrome have an increased risk of behavioral, social, and emotional difficulties compared with their unaffected peers. These problems include attention-deficit/hyperactivity disorder (ADHD); depression; anxiety; and autism spectrum disorder. Physical features related to 47,XYY syndrome can include increased belly fat, a large head (macrocephaly), unusually large teeth (macrodontia), flat feet (pes planus), fifth fingers that curve inward (clinodactyly), widely spaced eyes (ocular hypertelorism), and abnormal side-to-side curvature of the spine (scoliosis). These characteristics vary widely among people with this condition.
Precipitants
None
Provocation Tests
None.
Diagnostic Procedures
Rarely is suspected clinically. Best method to diagnose this condition is karyotype or chromosome microchip array. A diagnosis of XYY syndrome is made based upon a thorough clinical evaluation, a detailed patient history, and specialized tests (i.e., chromosomal analysis) that detect the presence of an extra Y chromosome (47,XYY karyotype) The 47,XYY syndrome is not inherited. The chromosomal change occurs as a random event.