Also known as 47,XYY; Jacobs syndrome; Double Y syndrome
What is XYY syndrome?
XYY syndrome, also referred to as 47,XYY or Double Y syndrome, is a sex chromosome aneuploidy characterized by the presence of an additional Y chromosome in males. Men and boys with XYY often have tall stature, low muscle tone, and risks for neurodevelopmental disorders including developmental delays (especially regarding expressive language), learning disabilities, ADHD, anxiety, and autism. The presence and severity of these symptoms are highly variable between individuals, with some boys having few symptoms while others are more significantly affected.
Who gets XYY syndrome?
Approximately 1 in 1,000 males are born with XYY, however many are not diagnosed and may go their entire lives without being diagnosed. The onset of prenatal cell-free DNA screening has increased the identification of XYY in newborns and active research is hoping to redefine the natural history of this condition when identified at birth.
What causes XYY syndrome?
XYY syndrome is caused by an extra Y chromosome in boys, due to the presence of an extra Y chromosome in the sperm at the time of conception, resulting from nondisjunction (when chromosomes do not divide properly), and is not typically inherited.
How is XYY syndrome diagnosed?
XYY syndrome is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose XYY syndrome include a karyotype (chromosome analysis looking at the number and structure of chromosomes in cells), a chromosomal microarray (a more detailed chromosome study looking for deletions or duplications across all chromosomes) or genetic sequencing (reading through the DNA sequence carried on the chromosomes). XYY may be suspected based on physical or neurodevelopmental differences during childhood and can be identified before birth by prenatal screening and/or diagnostic testing, such as amniocentesis.
What is the treatment for XYY syndrome?
Treatments for XYY syndrome are specific to managing symptoms, which can be highly variable and may include therapies for developmental delays, as well as psychological and/or academic support, when indicated. Puberty should be monitored by a primary care physician with referral to endocrinology given any concerns to ensure hormone treatment is provided if indicated.
Frequently Asked Questions
Why did I get XYY syndrome?
XYY syndrome is not caused by anything a person does or doesn't do, as it results from a biological process in which the chromosomes misdivide, called nondisjunction.
Will my XYY syndrome get worse?
The symptoms associated with XYY syndrome may or may not change over time. Some symptoms, such as developmental delays or learning disabilities, may be present from a very young age, whereas other symptoms, such as tall stature, may become more apparent later in childhood.
What things can I discuss with my primary care physician about XYY syndrome?
While there is no standard of care guideline in XYY syndrome, there have been many articles published in medical literature to help guide physicians on how to best care for patients with this condition. Talk with your doctor about your concerns or your child's struggles to ensure that appropriate referrals and evaluations are being pursued. Since fertility interventions are possible, even though infertility is associated with this condition, referrals for further fertility evaluation may also be helpful.