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Aase Syndrome (or Aase-Smith Syndrome II) is a highly infrequent disorder.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Aase-Smith Syndrome II
  • Congenital Anemia-Triphalangeal Thumb Syndrome
  • Hypoplastic Anemia-Triphalangeal Thumbs, Aase-Smith Type

What is Aase Syndrome? (Definition/Background Information)

  • Aase Syndrome (or Aase-Smith Syndrome II) is a highly infrequent disorder. Individuals with this disorder show a variety of signs and symptoms at birth, characteristic features of which include, congenital hypoplastic anemia and triphalangeal thumbs
  • Congenital hypoplastic anemia is a condition, in which the population of red blood cells is decreased because of reduced bone marrow production
  • Triphalangeal thumb is a term meant to denote 3 phalanges (finger bones) in the thumb, as against 2 phalanges in a normally developed thumb
  • The presence of both congenital hypoplastic anemia and triphalangeal thumbs, are necessary for a clinical diagnosis of Aase Syndrome
  • The prognosis of this disorder depends upon the severity of the syndrome

Who gets Aase Syndrome? (Age and Sex Distribution)

  • Aase Syndrome is a rare disorder that is manifested at birth. Current evidence suggests that in some individuals, the condition may be genetic; it being inherited in an autosomal recessive manner. The cause of Aase Syndrome is uncertain, at this point in time
  • Both the male and female sexes, are equally predisposed towards the syndrome

What are the Risk Factors for Aase Syndrome? (Predisposing Factors)

  • The direct cause for Aase Syndrome is unknown though some cases are known to be genetic. In a majority, the syndrome is not inherited/familial - indicating that it does not run in families. In such cases, if an individual has Aase syndrome, then there does not appear to be an increased risk for the family members
  • However, there are a few occasions where Aase Syndrome is genetically inherited

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Aase Syndrome? (Etiology)

  • In a majority of cases, the cause of Aase Syndrome is unknown
  • There have only been an estimated 20 cases of Aase Syndrome reported in medical literature. Research is still being conducted to establish the origins of the syndrome, to detect the exact genes involved, and patterns of inheritance
  • In a minority of cases, the condition is an inherited genetic disorder, though location/origin of the specific genetic defect is unknown. Nevertheless, it is known that the disorder is inherited in an autosomal recessive manner, in such cases

What are the Signs and Symptoms of Aase Syndrome?

Individuals with Aase Syndrome demonstrate a variety of physical signs and symptoms. The presence of congenital hypoplastic anemia (very low red blood cell count at birth) and triphalangeal thumbs (3-bones in the thumb, triple-jointed thumbs) is characteristic and important features of Aase Syndrome. Therefore, the condition is also called Congenital Anemia-Triphalangeal Thumb Syndrome.

A diagnosis of Aase Syndrome is usually made, very early in life (typically during infancy). Other signs and symptoms include:

  • Delayed growth of the child
  • Delayed closure of the fontanels (membranous gaps) of the skull bones
  • Narrowing of the shoulders
  • Abnormal extension of the joints due to do congenital contractions
  • Abnormally formed ears
  • Cleft palate
  • Drooping of the eyelids
  • Pale color of skin

How is Aase Syndrome Diagnosed?

A diagnosis of Aase Syndrome would involve:

  • Complete physical examination with evaluation of family medical history
  • Complete blood count will show decreased number of red cells (anemia) and white blood cells (leukopenia)
  • Individuals with Aase Syndrome may have congenital heart disease. The most common one noted is a ventricular septal defect (VSD). VSD can be diagnosed using echocardiogram diagnostic modality
  • X-rays of the skeletal system will demonstrate various abnormalities, including triphalangeal thumbs, growth retardation in long bones of the body, and delayed closure of the skull fontanels
  • Bone marrow biopsy may demonstrate decreased similarity of the bone marrow, which causes hypoplastic anemia and leukopenia

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Aase Syndrome?

A few complications of Aase Syndrome include:

  • Individuals have reduced ability to carry oxygen in blood because of anemia, due to which they easily tire and become weak
  • Congenital heart defects can also result in heart failure
  • Individuals with this syndrome do not have a normal life span; early deaths and stillbirths have been reported with this condition

How is Aase Syndrome Treated?

Treatment measures for Aase Syndrome:

  • Due to the presence of anemia, patients are treated with packed red blood cell transfusion(s), to help increase the body ability to carry oxygen. Blood transfusions are generally started early; in many instances, the transfusions are given within a child’s first year of life
  • A bone marrow transplant is also a modality to treat leukopenia and hypoplastic anemia
  • Steroidal therapy using medications, such as prednisone, is helpful in older individuals. Steroidal therapy is generally not recommended for children less than one year of age because it may affect brain development
  • Heart defects may be corrected through surgery

How can Aase Syndrome be Prevented?

  • Aase Syndrome is a very rare condition that is difficult to prevent. The direct cause of this disorder (genetic or otherwise), is not known at this point in time
  • However, early recognition and treatment can increase an individual’s quality of life
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child

What is the Prognosis of Aase Syndrome? (Outcomes/Resolutions)

  • The prognosis of Aase syndrome depends upon the severity of the syndrome. Individuals with severe forms of the disorder may have a shortened life span
  • Hypoplastic anemia gradually gets better with time (it may take years), resulting in decreased dependence on blood transfusions. The bone marrow recovery may take many more years
  • White blood cells (leukocytes) are an integral part of an immune system. Decreased leukocytes (leukopenia) due to decreased production in bone marrow may also cause damaging effects on the body immune system. Depending on the severity of leukopenia, individuals with Aase Syndrome may be prone to a variety of infections. Greater the degree of leukopenia, more severe is the infection
  • In those with severe congenital heart defects (such as a large ventricular septal defect), heart failure may occur, resulting in early death
  • Stillbirths have been associated with Aase Syndrome

Additional and Relevant Useful Information for Aase Syndrome:

Blackfan-Diamond anemia is a blood-related genetic disorder, with a reduced blood cell count and physical defects, such as thumb deformities, head and neck abnormalities, etc. Some features of Aase Syndrome overlap with those of Blackfan-Diamond anemia.

What are some Useful Resources for Additional Information?

National Organization for Rare Disorders (NORD)
55 Kenosia Avenue Danbury, CT 06810
Phone: (203) 744-0100
Toll-Free: (800) 999-6673
Fax: (203) 798-2291
Email: orphan@rarediseases.org
Website: http://www.rarediseases.org

National Heart, Lung, and Blood Institute (NHLBI)
6701 Rockledge Drive P.O. Box 30105 Bethesda, MD 20824-0105
Phone: (301) 592-8573
Fax: (301) 592-8563
Email: nhlbiinfo@nhlbi.nih.gov
Website: http://www.nhlbi.nih.gov

National Society of Genetic Counselors
330 N. Wabash Avenue, Suite 2000 Chicago, IL 60611
Phone: (312) 321-6834
Fax: (312) 673-6972
Email: nsgc@nsgc.org
Website: http://nsgc.org 

References and Information Sources used for the Article:

http://www.nlm.nih.gov/medlineplus/ency/article/001662.htm (accessed on 10/30/2013)

http://healthtools.aarp.org/galecontent/aase-syndrome/1 (accessed on 10/30/2013)

https://www.rarediseases.org/rare-disease-information/rare-diseases/byID/106/viewAbstract (accessed on 10/30/2013)

Helpful Peer-Reviewed Medical Articles:

Kondoh, T., & Matsumoto, T. (1996). [Aase syndrome]. Ryoikibetsu Shokogun Shirizu(15), 232-233.

Matsuo, M. (2001). [Aase-Smith syndrome]. Ryoikibetsu Shokogun Shirizu(33), 85-86.

van Weel-Sipman, M., Van de Kamp, J. J. P., & De Koning, J. (1977). A female patient with “Aase syndrome”. The Journal of pediatrics, 91(5), 753-755.

Muis, N., Beemer, F. A., Van Dijken, P., & Klep-de Pater, J. M. (1986). The AASE syndrome. European journal of pediatrics, 145(1-2), 153-157.

Hing, A. V., & Dowton, S. B. (1993). Aase syndrome: novel radiographic features. American journal of medical genetics, 45(4), 413-415.

Higginbottom, M. C., Jones, K. L., Kung, F. H., Koch, T. K., & Boyer, J. L. (1978). The Aase syndrome in a female infant. Journal of medical genetics, 15(6), 484-486.

Pfeiffer, R. A., & Ambs, E. (1983). The Aase syndrome: hereditary autosomal recessive congenital erythropoiesis insufficiency and triphalangeal thumbs. Monatsschrift Kinderheilkunde: Organ der Deutschen Gesellschaft fur Kinderheilkunde, 131(4), 235.

Van Weel-Sipman, M., Vandecamp, J. J. P., & DeKoning, J. (1978). A female with" Aase syndrome". Plastic and Reconstructive Surgery, 62(1), 148.

D'avanzo, M., Pistoia, V., Santinelli, R., Tolone, C., Toraldo, R., Corcione, A., ... & Lafusco, F. (1994). Heterogeneity of the erythropoietic defect in two cases of Aase-Smith syndrome. Pediatric hematology and oncology, 11(2), 189-195.

Canun, S. (1990). AASE-SMITH SYNDROME. Radiology of Syndromes, Metabolic Disorders, and Skeletal Dysplasias, 4.