FG syndrome

FG syndrome is a rare genetic condition, caused by mutations on the X chromosome, that produces a combination of physical anomalies and developmental delay largely in boys. Most cases trace to mutations in the MED12 gene, which helps regulate the activity of other genes during development, though a smaller number of cases involve other X-linked genes including FMR1, FLNA, UPF3B, CASK, MECP2 and ATRX, each producing a somewhat different pattern of features grouped under the same name. Affected children typically show intellectual disability, hyperactivity, an unusually large head, low muscle tone, severe chronic constipation, and characteristic facial features including a drooping expression and a thin upper lip. The condition can be life-threatening in infancy, with roughly one in three affected infants dying of respiratory infection, though people who survive early childhood have lived past age fifty. Because there is no single agreed clinical test, diagnosis relies on recognizing the overall pattern of developmental delay, X-linked family history, the characteristic facial appearance, broad thumbs and other congenital anomalies together, often supported by genetic testing for the known causative genes. There is no cure, and care is coordinated across a team of specialists addressing each child's specific medical, developmental and behavioral needs.