Aarskog–Scott syndrome

Overview

Aarskog–Scott syndrome (AAS), also known as faciogenital dysplasia, is a rare genetic condition that primarily affects the development of facial features, muscles, skeleton, genitals, and stature. It is most commonly diagnosed in males, though females who carry the gene mutation may exhibit mild features. First described in the 1970s by Dagfinn Aarskog and Charles I. Scott Jr., the syndrome is typically noticeable in early childhood and presents with a characteristic facial appearance and short stature.

Causes

Aarskog–Scott syndrome is caused by mutations in the FGD1 gene, located on the X chromosome (Xp11.21). This gene is responsible for producing a protein involved in cell signaling pathways that regulate growth and development, particularly during embryonic stages.

The condition follows an X-linked recessive inheritance pattern. Because males have only one X chromosome, they are more severely affected. Females, who have two X chromosomes, are usually carriers and may display mild physical signs without significant developmental issues.

Symptoms

Symptoms of Aarskog–Scott syndrome vary in severity and may include features affecting the face, body, genitals, and musculoskeletal system. Common clinical characteristics include:

Facial Features:

• Rounded face with a broad forehead

• Wide-set eyes (hypertelorism)

• Droopy eyelids (ptosis)

• Small nose with upturned nostrils

• Wide philtrum and a prominent upper lip

Skeletal and Growth Abnormalities:

• Short stature, particularly in childhood

• Delayed bone age and short fingers or toes (brachydactyly)

• Joint laxity, especially in fingers

• Sunken chest (pectus excavatum)

Genital Anomalies (in males):

• Shawl scrotum (scrotal skin that surrounds the penis)

• Undescended testes (cryptorchidism)

• Delayed puberty

Other Possible Features:

• Mild to moderate intellectual disability or learning difficulties

• Hyperactivity or attention-deficit behaviors

• Dental anomalies, such as delayed eruption or misaligned teeth

• Umbilical hernia or inguinal hernia

Diagnosis

Diagnosis is based on clinical evaluation and confirmed through genetic testing. Key diagnostic steps include:

• Physical examination: Identification of characteristic facial and skeletal features

• Family history assessment: Especially in families with known cases of AAS

• Radiographic imaging: May reveal delayed bone age or skeletal anomalies

• Genetic testing: Identification of mutations in the FGD1 gene

Carrier testing and prenatal diagnosis may be considered in families with a known mutation.

Treatment

There is no cure for Aarskog–Scott syndrome. Treatment is supportive and focused on addressing specific symptoms. A multidisciplinary team approach is often helpful and may include:

• Growth monitoring: With consideration for hormone therapy in cases of significant short stature

• Orchidopexy: Surgical correction of undescended testes

• Dental care: Orthodontic treatment for dental anomalies

• Educational support: For learning or behavioral difficulties

• Physical or occupational therapy: To improve joint mobility or muscle strength

• Psychological support: For attention or behavioral issues

Prognosis

The overall prognosis for individuals with Aarskog–Scott syndrome is generally good, especially with early intervention and supportive care. Most children grow up to lead independent lives. While physical features may become less noticeable with age, short stature and minor developmental challenges may persist. Life expectancy is typically normal.