TAR syndrome; congenital amegakaryocytic thrombocytopenia
- Thrombocytopenia and absent radii (TAR)
syndrome is also known as congenital amegakaryocytic thrombocytopenia
- Inheritance is complex but usually
autosomal recessive.
- The classic finding of absent radii
with thumbs present
differentiates it from Fanconi anemia.
- Anomalies of hands, shoulders, and lower
limbs also may be seen. Also CHD.
- TAR presents with
isolated
thrombocytopenia in the neonate, but 45% of patients ultimately develop aplastic anemia.;
if baby survives, hematological defects become less severe
Several other disorders are associated with
skeletal anomalies and hematologic disease.
- Fanconi's Anemia (no thumb or
radius)
-
Schwachman-Diamond Syndrome
(pancreas)
- Dyskeratosis Congenita
(skin and nail changes)
- TAR syndrome (thrombocytopenia, absent
radius, thumbs present)
-
Diamond-Blackfan Anemia
(RBC hypoplasia)
- Bloom syndrome (predisp to leukemia, malignancies)
- Other rare disorders associated with both
skeletal anomalies and hematologic disorders include
- familial aplastic anemia syndromes
- cartilage-hair hypoplasia
- Dubowitz syndrome
- Seckel syndrome
- Poland syndrome
- Acquired disorders also may be associated
with both hematologic and
skeletal abnormalities. Children who have newly diagnosed acute lymphoblastic
leukemia often present with bone pain and generalized radiologic signs, but
they do not have congenital abnormalities.
References:
Alter BP, Young NS. The bone marrow failure syndromes. In: Nathan DG,
Orkin SH, Oski FA, Ginsburg D, eds. Nathan and Oski's Hematology of
Infancy and Childhood. 5th ed. Philadelphia, Pa: WB Saunders Co; 1998:
286-301
Freedman MH. Inherited forms of bone marrow failure. In: Hoffman R,
Benz EJ Jr, Shattil SJ, et al, eds. Hematology: Basic Principles and
Practice. 3rd ed. New York, NY: Churchill Livingstone; 2000:260-297