Thrombocytopenia 1

Alternative Names

  • THC1
  • THC
  • Thrombocytopenia, X-Linked
  • XLT
  • Thrombocytopenia, X-Linked, 1
  • Thrombocytopenia, X-Linked, Intermittent

Associated Genes

WAS Gene
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WHO-ICD-10 version:2010

Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

Coagulation defects, purpura and other haemorrhagic conditions

OMIM Number


Mode of Inheritance

X-linked Recessive

Gene Map Locus



The WAS-related disorders including: Wiskott-Aldrich syndrome, X-linked thrombocytopenia (XLT), and X-linked congenital neutropenia (XLN), are a spectrum of disorders of hematopoietic cells, with predominant defects of platelets and lymphocytes. X-linked thrombocytopenia (XLT) is a rare recessive hereditary disorder, characterized by isolated thrombocytopenia with small-sized platelets, which primarily affects males. Affected patients usually have abnormally small platelets as well as microthrombocytopenia. Individuals with X-linked thrombocytopenia bruise easily or have spontaneous bleeding. Also some patients experience cerebral hemorrhage, which can cause brain damage that can be life-threatening.

The diagnosis of X-linked thrombocytopenia is suspected in males with congenital thrombocytopenia and small platelet size. It could be confirmed by molecular genetic testing for the variant in WAS gene.

Molecular Genetics

Mutations in the WAS gene, mapped to chromosome Xp11.23, are the cause of X-linked recessive thrombocytopenia disorder. These mutations lead to the production of an altered WAS protein that cannot efficiently relay signals from the cell membrane to the actin cytoskeleton. These signaling problems affect platelets, impairing their development in the affected patients.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
313900.2.1LebanonMaleYesNo Thrombocytopenia; Epistaxis; Gingi... NM_000377.3:c.134C>THemizygousX-linked, RecessiveHo et al. 2001
313900.2.2LebanonMaleYesNo Thrombocytopenia... NM_000377.3:c.134C>THemizygousX-linked, RecessiveHo et al. 2001 Sibling of 313900.2....
313900.2.3LebanonMaleYesNo Abnormal platelet count,; Epistaxis; ... NM_000377.3:c.134C>THemizygousX-linked, RecessiveHo et al. 2001 Sibling of 313900.2....
313900.2.4LebanonMaleYesNo Thrombocytopenia... NM_000377.3:c.134C>THemizygousX-linked, RecessiveHo et al. 2001 Sibling of 313900.2....

Other Reports

Saudi Arabia

Knox-Macaulay et al. (1993) described a Saudi Arabian boy with X-linked recessive thrombocytopenia. In his early childhood, he presented with thrombocytopenia, morphologically large and normal sized platelets, increased mean platelet volume, and a hypermegakaryocytic bone marrow. He bled excessively after neonatal circumcision. He also suffered from recurrent bouts of epistaxis from the age of 6-months. At the age of 3-years, he had essential autoimmune thrombocytopenic purpura (EATP). He had two affected brothers with less severe bleeding episodes, suggesting an X-linked recessive thrombocytopenia disorder. Results of DNA analysis with the probe M27-beta were consistent with X-linkage and indicated also that the locus of the relevant gene lies close to or is identical to the WAS locus.

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