Definition

Aase syndrome is a rare disorder that involves anemia and certain joint and skeletal deformities.

Alternative Names

Aase-Smith syndrome; Hypoplastic anemia - triphalangeal thumbs, Aase-Smith type; Diamond-Blackfan with AS-II; Aase-Smith I syndrome; Hydrocephalus-cleft palate-joint contractures syndrome

Causes

Many cases of Aase syndrome occur without a known reason and are not passed down through families (inherited). However, some cases (45%) have been shown to be inherited. These are due to a change in 1 of 20 genes important for making protein correctly (the genes make ribosomal proteins).

This condition is similar to Diamond-Blackfan anemia, and the two conditions should considered the same. A missing piece on chromosome 19 is found in some people with Diamond-Blackfan anemia.

The anemia in Aase syndrome is caused by poor development of the bone marrow, which is where blood cells are formed.

Symptoms

Symptoms may include:

• Absent or small knuckles
• Cleft palate
• Deformed ears
• Droopy eyelids
• Inability to fully extend the joints from birth
• Narrow shoulders
• Pale skin
• Triple-jointed thumbs

Exams and Tests

Your health care provider will perform a physical exam. Tests that may be done include:

• Bone marrow biopsy
• Complete blood count (CBC)
• Echocardiogram
• X-rays

Treatment

Treatment may involve blood transfusions in the first year of life to treat anemia.

A steroid medicine called prednisone has also been used to treat anemia associated with Aase syndrome. However, it should only be used after reviewing the benefits and risks with a provider who has experience treating anemias.

A bone marrow transplant may be necessary if other treatment fails.

Outlook (Prognosis)

The anemia tends to improve with age.

Possible Complications

Complications related to anemia include:

• Fatigue
• Decreased oxygen in the blood
• Weakness

Heart problems can lead to a variety of complications, depending on the specific defect.

Severe cases of Aase syndrome have been associated with stillbirth or early death.

Prevention

Genetic counseling is recommended if you have a family history of this syndrome and wish to become pregnant.

References

Gallagher PG. The neonatal erythrocyte and its disorders. In: Orkin SH, Fisher DE, Ginsburg D, Look AT, Lux SE, Nathan DG, eds. Nathan and Oski's Hematology and Oncology of Infancy and Childhood. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 2.

National Center for Advancing Translational Sciences. Genetic and Rare Diseases Information Center website. Aase-Smith syndrome. rarediseases.info.nih.gov/diseases/5642/aase-smith-syndrome. Updated February 2023. Accessed September 25, 2023.

Thornburg CD. Congenital hypoplastic anemia (Diamond-Blackfan anemia). In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 475.