Type of disease: Rare conditions
FG syndrome (FGS) is a genetic condition that affects many parts of the body and occurs almost exclusively in males. “FG” represents the surname initials of the first individuals diagnosed with the disorder. People with FGS frequently have intellectual disability ranging from mild to severe, hypotonia, constipation and/or anal anomalies, a distinctive facial appearance, broad thumbs and great toes, a large head compared to body size (relative macrocephaly), and abnormalities of the corpus callosum. Medical problems including heart defects, seizures, undescended testicle, and an inguinal hernia have also been reported in some affected individuals. Researchers have identified five regions of the X chromosome that are linked to FGS in affected families. The condition is called FGS1 when it is caused by a change (mutation) in a gene called MED12. FGS2 is caused by mutations in the FLNA gene. The genes responsible for FGS3, FGS4, and FGS5 remain unknown. FGS is inherited in an X-linked recessive pattern. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.