ATR-X syndrome

ATR-X syndrome, also known as alpha-thalassemia mental retardation syndrome, is an X-linked recessive condition caused by a mutation in the ATRX gene on the X chromosome. Affected males typically show moderate intellectual disability together with distinctive physical characteristics, including coarse facial features, microcephaly, hypertelorism, a depressed nasal bridge, a tented upper lip and an everted lower lip. The condition also involves mild or moderate anemia associated with alpha-thalassemia, linking the neurological and blood-related features to the same underlying gene defect. Female carriers of the mutated gene generally show no specific signs, though some display skewed X chromosome inactivation, which can occasionally produce milder features in a small number of carriers.