TAR
MCID: THR009
MIFTS: 53
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Thrombocytopenia-Absent Radius Syndrome (TAR)
Categories:
Blood diseases, Bone diseases, Fetal diseases, Genetic diseases, Rare diseases
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MalaCards integrated aliases for Thrombocytopenia-Absent Radius Syndrome:
Characteristics:Orphanet epidemiological data:58
thrombocytopenia-absent radius syndrome
Inheritance: Autosomal recessive; Prevalence: 1-9/1000000 (Europe); Age of onset: Antenatal,Neonatal; OMIM®:57 (Updated 05-Mar-2021)
Inheritance:
autosomal recessive
Miscellaneous:
approximately 40% of patients die within newborn period severity of hematologic disorder decreases with advancing age HPO:31
thrombocytopenia-absent radius syndrome:
Onset and clinical course death in infancy Inheritance autosomal recessive inheritance GeneReviews:25
Penetrance Penetrance appears to be complete in individuals who have biallelic rbm8a pathogenic variants.
Classifications:
MalaCards categories:
Global: Genetic diseases Rare diseases Fetal diseases Anatomical: Bone diseases Blood diseases
ICD10:
32
33
Orphanet: 58
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MedlinePlus Genetics :
43
Thrombocytopenia-absent radius (TAR) syndrome is characterized by the absence of a bone called the radius in each forearm and a shortage (deficiency) of blood cells involved in clotting (platelets). This platelet deficiency (thrombocytopenia) usually appears during infancy and becomes less severe over time; in some cases the platelet levels become normal.Thrombocytopenia prevents normal blood clotting, resulting in easy bruising and frequent nosebleeds. Potentially life-threatening episodes of severe bleeding (hemorrhages) may occur in the brain and other organs, especially during the first year of life. Hemorrhages can damage the brain and lead to intellectual disability. Affected children who survive this period and do not have damaging hemorrhages in the brain usually have a normal life expectancy and normal intellectual development.The severity of skeletal problems in TAR syndrome varies among affected individuals. The radius, which is the bone on the thumb side of the forearm, is almost always missing in both arms. The other bone in the forearm, which is called the ulna, is sometimes underdeveloped or absent in one or both arms. TAR syndrome is unusual among similar malformations in that affected individuals have thumbs, while people with other conditions involving an absent radius typically do not. However, there may be other abnormalities of the hands, such as webbed or fused fingers (syndactyly) or curved pinky fingers (fifth finger clinodactyly). Some people with TAR syndrome also have skeletal abnormalities affecting the upper arms, legs, or hip sockets.Other features that can occur in TAR syndrome include malformations of the heart or kidneys. Some people with this disorder have unusual facial features including a small lower jaw (micrognathia), a prominent forehead, and low-set ears. About half of affected individuals have allergic reactions to cow's milk that may worsen the thrombocytopenia associated with this disorder.
MalaCards based summary : Thrombocytopenia-Absent Radius Syndrome, also known as tar syndrome, is related to chromosome 1q21.1 deletion syndrome, 1.35-mb and amegakaryocytic thrombocytopenia, congenital. An important gene associated with Thrombocytopenia-Absent Radius Syndrome is RBM8A (RNA Binding Motif Protein 8A), and among its related pathways/superpathways are Embryonic and Induced Pluripotent Stem Cell Differentiation Pathways and Lineage-specific Markers and Visual Cycle in Retinal Rods. Affiliated tissues include bone, brain and kidney, and related phenotypes are thrombocytopenia and abnormality of coagulation Disease Ontology : 12 A chromosomal deletion syndrome that is characterized by absence of the radius bone and platelet deficiency and bilateral absence of the radii with the presence of both thumbs and generally transient thrombocytopenia (less than 50 platelets/nL) and that has material basis in compound heterozygosity for a rare null mutation involving the RBM8A gene on chromosome 1q12 on 1 allele and 1 of 2 low-frequency noncoding single-nucleotide polymorphisms in RBM8A on the other. GARD : 20 TAR syndrome is characterized by the absence of a bone called the radius in each forearm, short stature, and thrombocytopenia. The thrombocytopenia often appears first in infancy but becomes less severe or returns to normal over time. Infants and young children are particularly vulnerable to episodes of severe bleeding which may occur in the brain and other organs. Children who survive this period and do not have damaging bleeding in the brain usually have a normal life expectancy and normal intellectual development. Other signs and symptoms vary but may include heart defects, kidney defects, and other skeletal abnormalities. About half of people with TAR syndrome also have difficulty digesting cow's milk. TAR syndrome is thought be caused by a deletion of genes on chromosome 1q21.1 in concert with another genetic change that has yet to be identified. Click here to see a diagram of chromosome 1. OMIM® : 57 The thrombocytopenia-absent radius syndrome (TAR) is characterized by reduction in the number of platelets and absence of the radius; preservation of the thumb distinguishes TAR from other syndromes that combine blood abnormalities with absence of the radius, such as Fanconi anemia (see 227650). Individuals with TAR have low numbers of megakaryocytes, platelet precursor cells that reside in bone marrow, and frequently present with bleeding episodes in the first year of life that diminish in frequency and severity with age. The severity of skeletal anomalies varies from absence of radii to virtual absence of upper limbs, with or without lower limb defects such as malformations of the hip and knee (summary by Albers et al., 2012). (274000) (Updated 05-Mar-2021) KEGG : 36 Thrombocytopenia-absent radius (TAR) syndrome is a rare autosomal recessive syndrome characterized by severe thrombocytopenia and bilateral defects in development of the radii at birth but with preservation of the thumb. Other physical abnormalities have been reported such as ulnar and humeral deformities, rib and cervical anomalies, cardiac lesions (usually septal defects), gastrointestinal and genitourinary abnormalities. Cow's milk allergy is highly prevalent in patients with TAR syndrome. TAR syndrome is caused by the compound (bi-allelic) inheritance of one of two noncoding single-nucleotide variants and a null allele in RBM8A. Clinical management is based on presentation, with platelet transfusions as required for thrombocytopenia and orthopedic intervention for functional optimization of upper limbs. UniProtKB/Swiss-Prot : 73 Thrombocytopenia-absent radius syndrome: An autosomal recessive disorder characterized by bilateral absence of the radii with the presence of both thumbs, thrombocytopenia, low numbers of megakaryocytes, and bleeding episodes in the first year of life. Thrombocytopenic episodes decrease with age. Skeletal anomalies range from absence of radii to virtual absence of upper limbs, with or without lower limb defects such as malformations of the hip and knee. Wikipedia : 74 TAR syndrome (thrombocytopenia with absent radius) is a rare genetic disorder that is characterized by... more...
GeneReviews:
NBK23758
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Human phenotypes related to Thrombocytopenia-Absent Radius Syndrome:58 31 (show top 50) (show all 70)
Symptoms via clinical synopsis from OMIM®:57 (Updated 05-Mar-2021)Clinical features from OMIM®:274000 (Updated 05-Mar-2021) |
Interventional clinical trials:
Cochrane evidence based reviews: upper extremity deformities, congenital |
MalaCards organs/tissues related to Thrombocytopenia-Absent Radius Syndrome:40
Bone,
Brain,
Kidney,
Bone Marrow,
Uterus,
Cortex,
Cerebellum
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Articles related to Thrombocytopenia-Absent Radius Syndrome:(show top 50) (show all 198)
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ClinVar genetic disease variations for Thrombocytopenia-Absent Radius Syndrome:6 (show all 16)
Copy number variations for Thrombocytopenia-Absent Radius Syndrome from CNVD:7 (show all 14)
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Cellular components related to Thrombocytopenia-Absent Radius Syndrome according to GeneCards Suite gene sharing:
Biological processes related to Thrombocytopenia-Absent Radius Syndrome according to GeneCards Suite gene sharing:
Molecular functions related to Thrombocytopenia-Absent Radius Syndrome according to GeneCards Suite gene sharing:
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