Sex chromosome abnormalities

Numerical abnormalities of the sex chromosomes are fairly
common and their effects are much less severe than those
caused by autosomal abnormalities. Sex chromosome
abnormalites are often detected coincidentally at amniocentesis
or during investigation for infertility. Many cases are thought to
cause no associated problems and to remain undiagnosed. The
risk of recurrence after the birth of an affected child is very low.
When more than one additional sex chromosome is present
learning disability or physical abnormality is more likely.