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Aarskog Syndrome

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Definition

Aarskog-Syndrome-Child

Also known as Aarskog-Scott Syndrome. Aarskog-Scott Syndrome is a genetic disorder that affects the development of many parts of the body. This condition mainly affects males, although females may have mild features of the syndrome.

People with Aarskog-Scott Syndrome have distinctive facial features, such as:

  • Widely spaced eyes.
  • Small nose.
  • Long area between the nose and mouth.
  • Widow's peak hairline (your hairline comes together in a downward v-shape at the center of your forehead).
  • Mild to moderate short stature during childhood.
  • Hand abnormalities, such as short fingers, curved pinky fingers, webbing of the skin between some fingers, a single crease across the palm.

Other abnormalities include:

  • Heart defects.
  • Split in the upper lip (cleft lip).
  • An opening in the roof of the mouth (cleft palate).

Most males have:

  • A shawl scrotum (the scrotum surrounds the penis instead of hanging below).
  • Undescended testes.
  • Soft out-pouching around the belly button (umbilical hernia) or in the lower abdomen (inguinal hernia).

Intellectual development varies widely, from mild learning and behavior problems, to normal intelligence, to severe intellectual disability.

About 20 percent of people with Aarskog-Scott Syndrome have mutations (a change in a DNA sequence) in the FGD1 gene (provides instructions for making a protein that functions as a guanine nucleotide exchange factor, which in turn activate proteins called GTPases which play an important role in chemical signaling within cells. GTPases are critical for various aspects of development before and after birth, particularly the development of bones).

The FGD1 protein is also involved in the remodeling of the extracellular matrix, which is the intricate lattice of protein and other molecules that forms in the spaces between cells.

The condition is inherited in an X-linked recessive pattern (mutations in genes in the X-chromosome).

Symptoms

Symptoms will vary from person to person. Most common symptoms include:

  • Wide feet.
  • Wide palms.
  • Drooping lower lip.
  • Wide set eyes.
  • Scrotum surrounds penis.
  • Short stature.
  • Disproportionately small hands.
  • Umbilical hernia.
  • Wide bridge of nose.
  • Cleft palate.

Inheritance

Aarskog Syndrome is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X-chromosome, which is one of the two sex chromosomes.

In males (who have only one X-Chromosome), one altered copy of the gene in each cell is sufficient to cause the condition.

In females (who have two X-Chromosomes) a mutation would have to occur in both copies of the gene that cause Aarskog Syndrome.

Because it is unlikely that females will have two altered copies of the gene, males are affected by X-linked recessive disorders much more frequently than females.

X-linked recessive conditions are unique in that fathers cannot pass X-linked traits to their sons, and all daughters of an affected male will be carriers (capable of passing on a genetic mutation associated with a disease).

Diagnosis

Diagnosis of Aarskog Syndrome may be based upon a thorough clinical evaluation, a detailed patient and family history, and the identification of characteristic findings. Genetic testing for FGD1 gene mutations is available to confirm the diagnosis.

Treatment

The treatment of Aarskog Syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Surgery may be necessary to treat specific congenital or structural malformations. Growth hormone treatment has been reported to improve height in some children. Genetic counseling is recommended for affected individuals and their families to clarify the genetic and clinical characteristics, the inheritance, and the recurrence risks of the condition in their families.

Other Information

The majority of patients present a good prognosis. Typically they have a good evolution into adulthood with an age-related improvement of mental status.








 

 

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