Definition: Triple X syndrome, also called trisomy X or 47,XXX, is characterized by the presence of one extra X chromosome in each of a female’s cells. This condition occurs in about 1 in 1,000 newborn girls. Five to 10 girls with triple X syndrome are born in the United States each day.
Most often, this chromosomal change causes no unusual physical features or medical problems. Females with triple X syndrome are sometimes taller than average and have an increased risk of learning disabilities and delayed speech and language skills.
Developmental delays and behavioral problems are also possible, but these characteristics vary widely among affected girls and women.
Most females with triple X syndrome have normal sexual development and are able to conceive children.
See also
chromosomal trisomies