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FGD1 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

FGD1 gene

The FGD1 gene provides instructions for making a protein that regulates chemical signaling within cells, playing a critical role in bone development and tissue maintenance.

Normal Function

The FGD1 gene provides instructions for making a protein that functions as a guanine nucleotide exchange factor (GEF). GEFs turn on (activate) proteins called GTPases, which play an important role in chemical signaling within cells. GTPases are turned off (inactivated) when they are attached (bound) to a molecule called GDP and are turned on (activated) when they are bound to another molecule called GTP.

The FGD1 protein activates the GTPase known as Cdc42 by stimulating the exchange of GDP for GTP. Once Cdc42 is active, it transmits signals that are critical for various aspects of development before and after birth, particularly the development of bones. The FGD1 protein may also be involved in maintenance (remodeling) of the extracellular matrix, which is the intricate lattice of proteins and other molecules that forms in the spaces between cells. Through this process, the protein appears to play a role in cell movement (migration) and the remodeling of blood vessels.

Health Conditions Related to Genetic Changes

Aarskog-Scott syndrome

More than 40 variants (also known as mutations) in the FGD1 gene have been found to cause Aarskog-Scott syndrome, a rare condition that occurs primarily in males. Affected boys typically have distinctive facial features, genital abnormalities, childhood short stature, and other skeletal abnormalities. The FGD1 gene variants lead to the production of an abnormally functioning FGD1 protein, which disrupts Cdc42 signaling. Altering the transmission of Cdc42 signals likely impairs normal development of bones and other tissues, resulting in the wide variety of abnormalities that occur in people with Aarskog-Scott syndrome.

Other Names for This Gene

  • AAS
  • faciogenital dysplasia protein
  • FGD1_HUMAN
  • FGDY
  • ZFYVE3

Frequently Asked Questions

FGD1 encodes a protein that activates the GTPase Cdc42, which is essential for cell shape, migration, and bone formation. Mutations disrupt Cdc42 signaling, impairing the normal development of bones, facial cartilage, and genital tissues, resulting in the characteristic short stature, distinctive facial features, and genital abnormalities.
Key signs include a broad nasal bridge, widow‑maker or widow‑maker‑like facial appearance, short stature, mild to moderate developmental delay, and genital anomalies such as hypospadias or cryptorchidism. If these features are present, a pediatrician may refer for genetic testing.
Because most FGD1 mutations are inherited in an X‑linked recessive pattern, carrier testing for the mother and prenatal testing (amniocentesis or CVS) for subsequent pregnancies are options. A genetic counselor can explain recurrence risks, discuss carrier status in relatives, and outline reproductive choices, including preimplantation genetic diagnosis.
Currently, treatment is supportive: growth hormone therapy may help with short stature, orthopedic care manages skeletal deformities, and early speech or developmental therapy addresses delays. No specific drug targets the defective FGD1 pathway yet, but ongoing research into Cdc42 modulators may offer future options.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.