Triple X syndrome Overview Triple X syndrome, also called trisomy X or 47,XXX, is a genetic disorder that affects about 1 in 1,000 females. Females normally have two X chromosomes in all cells — one X chromosome from each parent. In triple X syndrome, a female has three X chromosomes. Many girls and women with triple X syndrome don't experience symptoms or have only mild symptoms. In others, symptoms may be more apparent — possibly including developmental delays and learning disabilities. Seizures and kidney problems occur in a small number of girls and women with triple X syndrome. Treatment for triple X syndrome depends on which symptoms, if any, are present and their severity. Symptoms Signs and symptoms can vary greatly among girls and women with triple X syndrome. Many experience no noticeable effects or have only mild symptoms. Being taller than average height is the most typical physical feature. Most females with triple X syndrome experience normal sexual development and ha...