XXXY Syndrome

Also known as 48,XXXY

What is XXXY syndrome?

XXXY syndrome, also known as 48,XXXY, is a rare sex chromosome aneuploidy in males characterized by the presence of two extra X chromosomes (total karyotype: 48,XXXY). Symptoms include congenital anomalies, tall stature, testicular dysfunction, infertility, and neurodevelopmental disorders including developmental delays (especially regarding expressive language), learning and intellectual disabilities, ADHD, autism, anxiety, and behavior problems.

Who gets XXXY syndrome?

It is estimated that 1 in 17,000-50,000 males have XXXY syndrome.

What causes XXXY syndrome?

XXXY syndrome is caused by two extra X chromosomes in boys, most commonly due to the presence of extra Xs in the egg or sperm at the time of conception, resulting from nondisjunction (when chromosomes do not divide properly), and is not typically inherited.

How is XXXY syndrome diagnosed?

XXXY syndrome is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose XXXY 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). XXXY 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 XXXY syndrome?

Treatments for XXXY 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.