Also known as 48,XXYY
What is XXYY syndrome?
XXYY syndrome, or 48,XXYY, is a sex chromosome aneuploidy characterized by the presence of an additional X and additional Y chromosome in males. Though previously considered a variant of XXY or Klinefelter syndrome, XXYY is now recognized as a distinct condition with its own unique description and associated symptoms. Men and boys with XXYY often have tall stature, testicular dysfunction resulting in testosterone deficiency and infertility, low muscle tone, and higher risks for neurodevelopmental disorders including developmental delays (especially regarding expressive language), learning and intellectual disabilities, ADHD, autism and anxiety, as well as other congenital malformations and medical problems.
Who gets XXYY syndrome?
XXYY syndrome is rarer than sex chromosome trisomies, affecting approximately 1 in 18,000–40,000 males.
What causes XXYY syndrome?
XXYY syndrome is caused by an extra X and extra Y chromosome in boys, most commonly due to the presence of an extra X and 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 XXYY syndrome diagnosed?
XXYY syndrome is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose XXYY 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). XXYY 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 an amniocentesis.
What is the treatment for XXYY syndrome?
Treatments for XXYY syndrome are specific to managing symptoms, including testosterone treatment beginning in adolescence to complete puberty and support bone health, infertility treatment by microTESE and ICSI, therapies for developmental delays, as well as neurodevelopmental, psychological and academic interventions.
Frequently Asked Questions
Why did I get XXYY syndrome?
XXYY 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 XXYY syndrome get worse?
The symptoms associated with XXYY 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 XXYY syndrome?
While there is no standard of care guidelines in XXYY, 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.