FG syndrome, type 1

FG syndrome is a very rare genetically determined congenital disorder affecting both the physical appearance and the intellectual and behavioral functioning of affected individuals. Only a few hundred individuals with this condition have been documented worldwide, although the true number may be significantly higher. The designation “FG” represents the initials of the family in which this genetic syndrome was first described. The syndrome shows a wide spectrum of severity, ranging from mild to severe forms. Individuals with FG syndrome are typically friendly, curious, and often hyperactive, with a short attention span. Compared with other individuals with intellectual disability, they tend to enjoy social interaction and may be relatively self‑sufficient; however, their communication skills and verbal expression are often limited.

Causes

The disorder is caused by a mutation in one of the genes located on the X chromosome. Individuals affected by FG syndrome are almost exclusively male.

Diagnosis

The condition can be diagnosed by specialized genetic testing, which identifies the mutation on the X chromosome.

Treatment

Prevention of the congenital disorder is not possible, and no effective causal treatment exists. Intellectual disability requires special educational support. In cases of imperforate anus, surgical intervention is necessary to correct the anatomical defect and restore intestinal continuity.

• moderate to severe intellectual disability
• behavioral disorders – hyperactivity and attention deficits; individuals may be more difficult to manage, but are often friendly and sociable
• characteristic facial features – macrocephaly (enlarged head), hypertelorism (widely spaced eyes), small ears, small upper lip and enlarged lower lip, high forehead
• broad thumbs of the limbs
• hypotonia – reduced muscle tone
• congenital developmental anomalies of the gastrointestinal tract – imperforate anus, constipation
• abnormalities of the corpus callosum (the brain structure connecting the right and left hemispheres)
• possible congenital heart defects, seizures, undescended testes in males, inguinal hernia