Also known as tetrasomy X; 48,XXXX
What is 48,XXXX syndrome?
48,XXXX, also known as tetrasomy X, is a rare sex chromosome aneuploidy in females characterized by the presence of four X chromosomes in each cell, leading to variable neurodevelopmental symptoms including intellectual disability, speech and language disorders, executive dysfunction, and physical features such as low muscle tone and primary ovarian failure.
Who gets 48,XXXX syndrome?
XXXX syndrome is rarer than sex chromosome trisomies, and only affects females, but the exact prevalence is not known.
What causes 48,XXXX?
XXXX syndrome is caused by two extra X chromosomes in females most commonly due to the presence of extra X chromosomes in the sperm or egg at the time of conception, resulting from nondisjunction (when chromosomes do not divide properly), and is not typically inherited.
How is 48,XXXX diagnosed?
48,XXYY is a chromosome condition which can be diagnosed from blood tests. Tests that can diagnose 48,XXXX 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). 48,XXXX 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 48,XXXX?
Treatments for 48,XXXX are specific to managing symptoms, estrogen treatment beginning in adolescence to complete puberty and support bone health, therapies for developmental delays, as well as neurodevelopmental, psychological and academic interventions.