Risk Factors (Genetics & Inherited Conditions)
Etiology and Genetics (Genetics & Inherited Conditions)
Aarskog syndrome results from a mutation in the FGD1 gene, which is located on the short arm of the X chromosome at position p11.21. The inheritance pattern of this disease is typical of all sex-linked recessive mutations (those found on the X chromosome). Mothers who carry the mutated gene on one of their two X chromosomes face a 50 percent chance of transmitting this disorder to each of their male children. Female children have a 50 percent chance of inheriting the gene and becoming carriers like their mothers. Although females rarely express the syndrome fully, female carriers may occasionally show minor manifestations. Affected males will pass the mutation on to all of their daughters but to none of their sons.
The FGD1 gene specifies a guanine exchange factor, which is one of a class of proteins that acts via an intracellular signaling network to turn on other genes at appropriate times during embryonic and fetal development. The specific genes and pathways known to be activated by the FGD1 protein are involved with the cell growth and differentiation of cells destined to become components of skin, bone, and cartilage. The mouse has proven to be a useful animal model system for the study of this disorder, and the mouse data suggest that FGD1 signaling specifically affects the development of several different skeletal cell types, including chondrocytes, osteoblasts, and mesenchymal...
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Symptoms (Genetics & Inherited Conditions)
The main symptoms of Aarskog syndrome are disproportionately short stature, abnormalities of the head and face (including rounded face, wide-set eyes, slightly slanted eyes, drooping eyelids, a small nose, front-facing nostrils, an underdeveloped midportion of the face, a wide groove above the upper lip, a crease below the lower lip, folding of the top portion of the ear, and/or delayed teeth growth), and in some cases cleft lip or palate. Other symptoms may include a malformed scrotum; undescended testicles; small, wide hands and feet; short fingers and toes; mild webbing of fingers and toes or a simian crease in the palm of the hand; abnormalities of the sternum (mildly sunken chest); a protruding navel; inguinal hernias; ligament problems, resulting in hyperextension of the knees; and/or mild mental deficiencies (in about one-third of those affected).
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Screening and Diagnosis (Genetics & Inherited Conditions)
The doctor will ask about symptoms and medical history and will perform a physical exam. The diagnosis of Aarskog syndrome is usually based on facial characteristics. The diagnosis can be confirmed by X rays of the face and skull.
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Treatment and Therapy (Genetics & Inherited Conditions)
There is no known cure for Aarskog syndrome. Treatment is limited to surgical procedures to treat conditions caused by the disorder and supportive treatment. Orthodontic treatment is often needed as well. Because researchers have located abnormalities in the FGD1 gene in people with this syndrome, genetic testing for mutations in this gene may be available.
Treatment may include surgery to correct inguinal hernia, cleft lip or palate, or undescended testicles. In some cases, orthodontic treatment may help certain facial and dental abnormalities caused by the disorder. Supportive treatment generally includes educational assistance to those afflicted with mental deficiencies, including advice and supportive treatment for parents.
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Prevention and Outcomes (Genetics & Inherited Conditions)
Further Reading (Genetics & Inherited Conditions)
Assumpcao, F., et al. “Brief Report: Autism and Aarskog Syndrome.” Journal of Autism and Developmental Disorders 29, no. 2 (April, 1999): 179-181.
DiLuna, Michael, et al. “Cerebrovascular Disease Associated with Aarskog-Scott Syndrome.” Neuroradiology 49, no. 5 (May, 2007): 457-461.
EBSCO Publishing. Health Library: Aarskog-Scott Syndrome. Ipswich, Mass.: Author, 2009. Available through http://www.ebscohost.com.
Pasteris, N. G., et al. “Isolation, Characterization, and Mapping of Mouse Fgd3 Gene: A New Faciogenital Dysplasia (FGD1; Aarskog Syndrome) Gene Homologue.” Gene 242, nos. 1/2 (January, 25, 2000): 237-247.
Rimoin, David L., et al. Emery and Rimoin’s Principles and Practice of Medical Genetics. 5th ed. Philadelphia: Churchill Livingstone Elsevier, 2007.
Schwartz, C. E., et al. “Two Novel Mutations Confirm FGD1 Is Responsible for the Aarskog Syndrome.” European Journal of Human Genetics 8, no. 11 (November, 2000): 869.
Stevenson, Roger E. “Aarskog Syndrome.” In Management of Genetic Syndromes, edited by Suzanne B. Cassidy and Judith E. Allanson. 2d ed. Hoboken, N.J.: Wiley-Liss, 2005.
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Web Sites of Interest (Genetics & Inherited Conditions)
About Kids Health. http://www.aboutkidshealth.ca
Genetics Home Reference. http://ghr.nlm.nih.gov
Health Canada. http://www.hc-sc.gc.ca/index-eng.php
International Birth Defects Information Systems. http://www.ibis-birthdefects.org
National Organization for Rare Disorders. http://www.rarediseases.org
Ontario March of Dimes. http://www.marchofdimes.ca/dimes
United States National Library of Medicine. http://www.nlm.nih.gov
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Aarskog syndrome (Encyclopedia of Genetic Disorders)
Aarskog syndrome is an inherited disorder that causes a distinctive appearance of the face, skeleton, hands and feet, and genitals. First described in a Norwegian family in 1970 by the pediatrician Dagfinn Aarskog, the disorder has been recognized worldwide in most ethnic and racial groups. Because the responsible gene is located on the X chromosome, Aarskog syndrome is manifest almost exclusively in males. The prevalence is not known.
Aarskog syndrome is among the genetic disorders with distinctive patterns of physical findings and is confused with few others. Manifestations are present at birth allowing for early identification. The facial appearance and findings in the skeletal system and genitals combine to make a recognizable pattern. The diagnosis is almost exclusively based on recognition of these findings. Although the responsible gene has been identified, testing for gene mutations is available only in research laboratories. Aarskog syndrome is also called Faciogenital dysplasia, Faciogenitodigital syndrome, and Aarskog-Scott syndrome.
Aarskog syndrome is caused by mutations in the FGD1 gene, located...
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