Aarskog-Scott Syndrome
Aarskog-Scott Syndrome
Aarskog-Scott Syndrome (AAS), also known as Faciogenital Dysplasia, is a rare genetic disorder primarily affecting males. It is characterized by distinctive facial features, short stature, and genital abnormalities. The syndrome was first described by Dagfinn Aarskog in 1970 and further characterized by Charles I. Scott Jr. in 1971.
Key Points:
- Incidence: Rare, exact prevalence unknown
- Inheritance: X-linked recessive (primarily affects males)
- Genetic basis: Mutations in the FGD1 gene on the X chromosome
- Characterized by facial, skeletal, and urogenital abnormalities
Clinical Features
Aarskog-Scott Syndrome presents with a wide range of clinical features, varying in severity among affected individuals:
Craniofacial Features:
- Rounded face with broad forehead
- Widely spaced eyes (hypertelorism)
- Ptosis (drooping eyelids)
- Small nose with anteverted nostrils
- Long philtrum
- Widow's peak hairline
- Broad, flat nasal bridge
- Maxillary hypoplasia
Skeletal Abnormalities:
- Short stature
- Brachydactyly (short fingers)
- Clinodactyly (curved pinky fingers)
- Joint hyperextensibility
- "Shawl" scrotum (extending around base of penis)
- Inguinal hernia
- Cryptorchidism (undescended testes)
Other Features:
- Mild to moderate intellectual disability (in some cases)
- Delayed motor development
- Attention deficit hyperactivity disorder (ADHD)
- Friendly, outgoing personality
Diagnosis
Diagnosis of Aarskog-Scott Syndrome is based on clinical features and genetic testing:
Clinical Diagnosis:
- Presence of characteristic facial features
- Short stature
- Genital abnormalities
- Family history consistent with X-linked inheritance
Genetic Testing:
- Molecular genetic testing for mutations in the FGD1 gene
- Sequence analysis of FGD1
- Deletion/duplication analysis if sequence analysis is negative
Differential Diagnosis:
Consider other conditions with overlapping features, such as:
- Noonan syndrome
- Short stature-hyperkinesis-facial anomalies syndrome
- Robinow syndrome
Management
Management of Aarskog-Scott Syndrome is multidisciplinary and focuses on addressing specific symptoms:
- Growth monitoring and potential growth hormone therapy
- Surgical correction of:
- Cryptorchidism
- Inguinal hernia
- Severe ptosis
- Orthodontic and dental care
- Ophthalmic evaluation and management
- Developmental assessment and support:
- Early intervention programs
- Special education services if needed
- Occupational and physical therapy
- Psychological support and ADHD management
- Genetic counseling for family planning
Genetics
Genetic Basis:
- Caused by mutations in the FGD1 gene located on Xp11.21
- FGD1 gene encodes a guanine nucleotide exchange factor (GEF) for Cdc42
- Affects cell growth, differentiation, and bone development
Inheritance Pattern:
- X-linked recessive inheritance
- Primarily affects males
- Females can be carriers and may show mild features
Genetic Testing and Counseling:
- Molecular genetic testing to confirm diagnosis
- Carrier testing for at-risk female relatives
- Prenatal testing and preimplantation genetic diagnosis available
- Genetic counseling recommended for affected families
