Also known as Triple Y syndrome
What is XYYY syndrome?
XYYY syndrome, also known as 48,XYYY or X-triple Y syndrome, is an extremely rare sex chromosome aneuploidy characterized by the presence of one X chromosome and three Y chromosomes (total 48 chromosomes). Its prevalence is exceedingly low, with only a handful of postnatal cases reported in medical literature. The clinical phenotype of 48,XYYY syndrome is not well established due to case reports in literature, but available reports suggest that affected individuals may present with subtle dysmorphic features, relative height deficiency, and may require growth hormone therapy. There is also evidence of immune cell population differences and deregulation of genes associated with hematological malignancies, which may warrant long-term hemato-oncological surveillance.
Who gets XYYY syndrome?
XYYY syndrome is a very rare sex chromosome aneuploidy, with most cases described are mosaic, such as 45,X/48,XYYY, further complicating phenotype characterization and prevalence estimates.
What causes XYYY syndrome?
XYYY syndrome is caused by two extra Y chromosomes in boys, most commonly due to the presence of extra Y chromosomes in the sperm at the time of conception, resulting from nondisjunction (when chromosomes do not divide properly), and is not typically inherited.
How is XYYY syndrome diagnosed?
XYYY syndrome is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose XYYY 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). XYYY 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 XYYY syndrome?
Treatments for XYYY syndrome are specific to managing symptoms and monitoring for hemato-oncological problems, growth monitoring and hormone treatment if indicated, testosterone monitoring and treatment if indicated, as well as neurodevelopmental, psychological and academic interventions.