Also known as 49,XXXYY
What is 49,XXXYY syndrome?
49,XXXYY, also known as 49,XXXYY or "3X 2Y syndrome", is an extremely rare sex chromosome aneuploidy in males characterized by the presence of 3 X chromosomes and 2 Y chromosomes. There are very few cases reported in medical literature. Symptoms described include congenital and musculoskeletal abnormalities (including hips and forearms), developmental delays, intellectual disability, facial features, hypogonadism, genital abnormalities (micropenis and undescended testicles), and tremor.
Who gets 49,XXXYY?
49,XXXYY is an extremely rare sex chromosome aneuploidy with an unknown estimated prevalence.
What causes 49,XXXYY?
49,XXXYY is caused by 2 extra X and 1 extra Y chromosome in boys, most commonly due to the presence of extra chromosomes 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 49,XXXYY diagnosed?
49,XXXYY is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose 49,XXXYY 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). 49,XXXYY 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 49,XXXYY?
Treatments for 49,XXXYY are specific to managing symptoms, including testosterone treatment beginning in adolescence to complete puberty and support bone health, monitoring for musculoskeletal abnormalities (imaging or surgery if indicated), genital evaluations and surgical treatment as indicated, therapies for developmental delays, as well as neurodevelopmental, psychological and academic interventions.