Aarskog-Scott syndrome

Synonyms

8

Overview

Aarskog syndrome is an inherited disease that affects a person's height, muscles, skeleton, genitals, and appearance of the face. Inherited means that it is passed down through families.

The syndrome is named for Dagfinn Aarskog, a Norwegian pediatrician and human geneticist who first described it in 1970, and for Charles I. Scott, Jr., an American medical geneticist who independently described the syndrome in 1971.

Symptoms

The Aarskog–Scott syndrome is a disorder with short stature, hypertelorism, downslanting palpebral fissures, anteverted nostrils, joint laxity, shawl scrotum, and mental retardation. The physical phenotype varies with age and postpuberal males may have only minor remnantmanifestations of the prepuberal phenotype.

Growth

  • Mild to moderate short stature evident by 1–3 years of age
  • Delayed adolescent growth spurt

Performance

  • Slight (dull normal) to moderate mental deficiency
  • Hyperactivity and attention deficit
  • Social performance usually good

Face

  • Rrounded face
  • Widow's peak hairline
  • Wide-set eyes (hypertelorism)
  • Droopy eyelids (blepharoptosis)
  • Downslanting eye slits (palpebral fissures)
  • Small nose with nostrils tipped forward (anteverted)
  • Underdeveloped mid-portion of the face (maxilla)
  • Wide groove above the upper lip (broad philtrum)
  • Crease below the lower lip
  • Delayed eruption of teeth
  • Top portion (upper helix) of the ear folded over slightly

Hands and feet

  • Small, broad hands and feet
  • Short fingers and toes (brachydactyly)
  • In-curving of the 5th finger (clinodactyly)
  • Mild interdigital webbing, between fingers as well as toes
  • Single transverse "simian crease" in palm
  • Broad thumbs and big toes

Neck

  • Short neck
  • Webbing of sides of the neck

Chest

  • Mild pectus excavatum (sunken chest)

Abdomen

  • Protruding navel
  • Inguinal hernias

Genitalia

  • Shawl scrotum
  • Undescended testicles

Causes

Aarskog syndrome is a genetic disorder. It affects mainly males, but females may have a milder form. The condition is caused by changes (mutations) in a gene called "faciogenital dysplasia" (FGDY1).

Mutations in the FGDY1 gene cause some cases of Aarskog-Scott syndrome. The FGDY1 gene provides instructions for making a protein that turns on (activates) another protein called Cdc42, which transmits signals that are important for various aspects of embryonic development.
Mutations in the FGDY1 gene lead to the production of an abnormally functioning protein. These mutations disrupt Cdc42 signaling, which causes the wide variety of developmental abnormalities seen in Aarskog-Scott syndrome.

Only about 20 percent of people with this disorder have identifiable mutations in the FGDY1 gene. The cause of Aarskog-Scott syndrome in other affected individuals is unknown.

Prevention

Prenatal testing may be available for those with a family history of the condition or known mutation of the gene.

Diagnosis

Genetic testing may be available for mutations in the FGDY1 gene. Genetic counseling is indicated for individuals or families who may carry this condition, as there are overlapping features with Fetal alcohol syndrome.

Prognosis

Mild degrees of mental slowness may be present, but affected children usually have good social skills. Some males may exhibit reduced fertility.

Some recent findings have included cystic changes in the brain and generalized seizures[citation needed] . There may be difficulty growing in the first year of life in up to one-third of cases. Misaligned teeth may require orthodontic correction. An undescended testicle will require surgery.

Adenylosuccinate lyase deficiency (MIM 103050, ADSL) is a rare autosomal recessive disease causing severe mental retardation and/or autistic features.1,2 Seizures are often observed (80%),3 varying in age of onset (from newborn to late childhood) and nature (tonic-clonic, "suppression burst" pattern, West syndrome, etc.), and are very often resistant to all medication. Around 50% of the children show autistic-like behaviour.4 Microcephaly is rare (1/13 of reported cases). Non-specific anomalies of the brain, such as hypoplasia of the vermis, cerebral atrophy,5 lack of myelination,6 white matter anomalies,7 and lissencephaly4 have often been described.

Other Complications:

  • Low self-esteem
  • Social difficulties related to physical problems
  • Male infertility in those with both testes undescended
  • Problems with the structure of the heart
  • Accumulation of fluid in tissues of body (lymphedema, cystic hygroma)
  • Failure to thrive in infants.

Treatment

Similar to all genetic diseases Aarskog–Scott syndrome cannot be cured, although numerous treatments exist to increase the quality of life.

Surgery may be required to correct some of the anomalies, and orthodontic treatment may be used to correct some of the facial abnormalities. Trials of growth hormone have been effective to treat short stature in this disorder.

Resources

  • NIH
  • PubMed Health
  • National Institute of Health
  • CDC