Aarskog-Scott Syndrome
Description
Aarskog-Scott Syndrome (ASS), also known as faciogenital dysplasia, is a rare genetic disorder affecting growth and development. Characterized by distinct facial features, skeletal abnormalities, and genital anomalies, ASS impacts individuals in various ways. This blog delves into the intricacies of Aarskog-Scott Syndrome, exploring its signs, causes, diagnosis, management, and how individuals can thrive despite the challenges.
Genes Involved
Genes Involved:
Aarskog-Scott Syndrome is caused by mutations in the FGD1 gene, located on chromosome Xp22.3. This gene provides instructions for making a protein that plays a critical role in cell growth and development.
Recognizing the Signs and Symptoms
Recognizing the Signs and Symptoms:
Individuals with Aarskog-Scott Syndrome exhibit a range of characteristics, including:
- Facial Features: A broad forehead, widely spaced eyes (hypertelorism), a short nose with a flat bridge, and a small, receding chin.
- Skeletal Abnormalities: Short stature, short limbs, particularly the arms and legs, with the hands and feet being disproportionately small.
- Genital Anomalies: In males, a hypospadias (urethral opening on the underside of the penis) and cryptorchidism (undescended testicles) can occur. Females may have a widened distance between the labia.
- Other Possible Features: Heart defects, scoliosis (curvature of the spine), and mild intellectual disability.
Causes
Causes:
Aarskog-Scott Syndrome is a genetic disorder caused by a mutation in the FGD1 gene. These mutations can be inherited from a parent who carries the gene, or they can occur spontaneously (de novo) in a child without a family history of the disorder.
Inheritance/recurrence risk
Inheritance or Recurrence Risk:
Aarskog-Scott Syndrome is typically inherited in an X-linked recessive pattern. This means that the gene is located on the X chromosome, and females have two X chromosomes while males have one X and one Y chromosome. A female with a mutation in one of her X chromosomes is typically a carrier and may not have symptoms of the disorder. However, there is a 50% chance that she will pass the mutated gene to her sons, who will then develop the disorder. A male with a mutation in the FGD1 gene will always have Aarskog-Scott Syndrome.
If a parent with Aarskog-Scott Syndrome has children with a partner who does not carry the FGD1 gene mutation, each child has a 50% chance of inheriting the disorder.
The possibility of spontaneous (de novo) mutations in the FGD1 gene also exists, meaning the mutation may occur in the egg or sperm of a parent, leading to a child with ASS without a family history of the disorder.
