Sex Chromosome Aneuploidy
“What are X&Y chromosome variations?
X&Y chromosome variations refer to conditions in which a child has an abnormal number of sex chromosomes, also known as X&Y chromosomes.
Other words used to describe X&Y chromosome variations are sex chromosome anomaly, sex chromosome abnormality and sex chromosome aneuploidy.
How do X&Y chromosome variations affect boys and girls?
Males usually have one X and one Y chromosome, and females usually have two X chromosomes. Occasionally, because of problems with the formation of a parent’s sperm or egg, a child can be born with extra or too few sex chromosomes.
For reasons we don’t completely understand, children with X&Y chromosome variations can also have developmental delays, learning disabilities and social-emotional difficulties. Babies diagnosed prenatally or during infancy with an X&Y chromosome variation should be monitored closely during early developmental years (birth to 5), including standardized developmental assessments to determine if early interventions are needed. Children with an X&Y chromosome variation should have neuropsychological testing during early academic years to monitor for learning disabilities, attentional problems and social/emotional concerns. Boys with extra X chromosomes need to be seen by an endocrinologist during puberty to help monitor their testosterone levels. Girls who are missing an X chromosome (Turner syndrome) also need ongoing monitoring and treatment by endocrinology, cardiology and other specialties.
X&Y chromosome variations in males include:
- 47,XXY (Klinefelter syndrome)
- 47,XYY
- 48,XXYY
- 48,XXXY
- 49,XXXXY
X chromosome variations in females include:
- 45,X (Turner syndrome)
- 47,XXX (Trisomy X or Triple X)
- 48,XXXX (Tetrasomy X)
- 49,XXXXX (Pentasomy X)
What causes sex chromosome variations?
Children are born with X&Y chromosome variations. These conditions are caused by a problem in the division of the X and Y chromosomes during the formation of a parent’s egg or the sperm, which are then involved in conception. The exact cause is unknown, and these conditions are typically not inherited.” Read More
