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...
Thrombocytopenia-absent radius (TAR) syndrome Overview Thrombocytopenia-absent radius (TAR) syndrome is a rare genetic disorder characterized by the congenital absence of the radius bone in both forearms (with thumbs present) and low platelet count (thrombocytopenia), causing bleeding risks. It is an autosomal recessive condition, often involving mutations in the RBM8A gene. While the first year of life presents the highest risk for severe hemorrhage, prognosis improves as platelet counts often normalize over time. Symptoms Hematologic (Blood): Thrombocytopenia, causing low platelet counts, usually appears at birth or within the first few weeks/months of life. It causes petechiae (tiny purple spots), bruising, and potential hemorrhage. This often improves after the first year. Skeletal (Limbs) : Bilateral absence of the radius (the forearm bone on the thumb side) is a defining feature, resulting in short, malformed forearms. Unlike similar conditions, thumbs are present. Associat...