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TAR syndrome

TAR syndrome is an autosomal recessive disorder caused by biallelic variants in the RBM8A gene, one pathogenic variant on one allele and a rare variant on the other allele. The hallmarks are radius aplasia and thrombocytopenia.

Clinical Findings

Thrombocytopenia

Thrombocytopenia is characterized by a low platelet count and reduced magakaryoctes in the bone marrow. This results in an increased bleeding risk.

Bone Abnormalities

Typical of the disease is the absence of the radius bone and a preserved thumb, which is important for differentials. In severe cases the ulna bone and even the lower limbs may be involved.

Diagnosis

The diagnosis can be already suspected by antenatal ultrasound, but confirmed by molecular genetic testing.

Systematic

Inheritable platelet disorders
Alloimmune thrombocytopenia
Autoinflammatory periodic fever, immunodeficiency, and thrombocytopenia
Bernard-Soulier syndrome
Bleeding disorder platelet-type 9
Glycoprotein 1a deficiency
IVIC syndrome
MYH9 related disorders
Mediterranean macrothrombocytopenia
TAR syndrome
RBM8A
Thrombasthenia of Glanzmann and Naegeli
Thrombocythemia 3
Wiskott–Aldrich syndrome

References:

1.

Teufel M et al. (1983) Consanguinity in a Turkish family with thrombocytopenia with absent radii (TAR) syndrome.

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2.

Anyane-Yeboa K et al. (1985) Tetraphocomelia in the syndrome of thrombocytopenia with absent radii (TAR syndrome).

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3.

Luthy DA et al. (1979) Prenatal diagnosis of thrombocytopenia with absent radii.

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4.

Hall JG et al. (1969) Thrombocytopenia with absent radius (TAR).

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5.

Dignan PS et al. (1967) Phocomelia with congenital hypoplastic thrombocytopenia and myeloid leukemoid reactions.

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6.

Rabinowitz JG et al. (1967) Trisomy 18, esophageal atresia, anomalies of the radius, and congenital hypoplastic thrombocytopenia.

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7.

Armitage JO et al. (1978) Syndrome of thrombocytopenia and absent radii: qualitatively normal platelets with remission following spenectomy.

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8.

Schoenecker PL et al. (1984) Dysplasia of the knee associated with the syndrome of thrombocytopenia and absent radius.

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9.

None (1984) Radial aplasia and amegakaryocytic thrombocytopenia (TAR syndrome) among Nigerian children.

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10.

None (1987) Thrombocytopenia and absent radius (TAR) syndrome.

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11.

Ray R et al. (1980) Lower limb anomalies in the thrombocytopenia absent-radius (TAR) syndrome.

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12.

Luthy DA et al. (1981) Prenatal ultrasound diagnosis of thrombocytopenia with absent radii.

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13.

None (1981) Dactylaplasia in mice a two-locus model for development anomalies.

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14.

Feingold M et al. (1980) TAR syndrome: Dorsal pedal edema and excessive perspiration.

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15.

Edelberg SB et al. (1977) Congenital hypomegakaryocytic thrombocytopenia associated with bilateral absence of the radius - the TAR syndrome.

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16.

Johnson KR et al. (1995) Mapping the mouse dactylaplasia mutation, Dac, and a gene that controls its expression, mdac.

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17.

Whitfield MF et al. (1976) Cows' milk allergy in the syndrome of thrombocytopenia with absent radius.

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18.

Strippoli P et al. (1998) Mutational screening of thrombopoietin receptor gene (c-mpl) in patients with congenital thrombocytopenia and absent radii (TAR).

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19.

Ceballos-Quintal JM et al. (1992) TAR-like syndrome in a consanguineous Mayan girl.

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20.

Albers CA et al. (2012) Compound inheritance of a low-frequency regulatory SNP and a rare null mutation in exon-junction complex subunit RBM8A causes TAR syndrome.

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21.

Kaminsky EB et al. (2011) An evidence-based approach to establish the functional and clinical significance of copy number variants in intellectual and developmental disabilities.

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22.

Sidow A et al. (1999) A novel member of the F-box/WD40 gene family, encoding dactylin, is disrupted in the mouse dactylaplasia mutant.

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23.

Pfeiffer RA et al. (1975) The phocomelia-thrombocytopenia syndrome. A follow-up report.

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24.

Greenhalgh KL et al. (2002) Thrombocytopenia-absent radius syndrome: a clinical genetic study.

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25.

GROSS H et al. (1956) [Congenital hypoplastic thrombopenia with aplasia of the radius, a syndrome of multiple variations].

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26.

SHAW S et al. (1959) Congenital hypoplastic thrombocytopenia with skeletal deformaties in siblings.

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27.

Menghsol SC et al. (2003) Thrombocytopenia and absent radii, TAR syndrome: report of cerebellar dysgenesis and newly identified cardiac and renal anomalies.

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28.

Klopocki E et al. (2007) Complex inheritance pattern resembling autosomal recessive inheritance involving a microdeletion in thrombocytopenia-absent radius syndrome.

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29.

Skórka A et al. (2005) Thrombocytopenia-absent radius (tar) syndrome: a case with agenesis of corpus callosum, hypoplasia of cerebellar vermis and horseshoe kidney.

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30.

Donnenfeld AE et al. (1990) Prenatal diagnosis of thrombocytopenia absent radius syndrome by ultrasound and cordocentesis.

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31.

Ashinoff R et al. (1990) Thrombocytopenia-absent radii syndrome and lack of response to the pulsed dye laser.

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32.

van Haeringen A et al. (1989) Intermittent thrombocytopenia and absent radii: report of a patient with additional unusual manifestations.

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33.

Ward RE et al. (1986) Parent to child transmission of the thrombocytopenia absent radius (TAR) syndrome.

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34.

Homans AC et al. (1988) Defective megakaryocytopoiesis in the syndrome of thrombocytopenia with absent radii.

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35.

Schnur RE et al. (1987) Thrombocytopenia with absent radius in a boy and his uncle.

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