X-linked idiopathic thrombocytopenia

Wiskott Aldrich syndrome presenting as congenital thrombocytopenia

The application of molecular biology to haematology has provided the opportunity to revisit previous diagnoses, many of which can now be redefined. This report is on a local family previously diagnosed and published as having X-linked thrombocytopenia in 1974, and shows how the application of molecular screening has confirmed the true diagnosis of Wiskott Aldrich syndrome.

X-linked thrombocytopenia and Wiskott-Aldrich syndrome are allelic diseases with mutations in the WASP gene

X-linked thrombocytopenia (XLT) is a rare recessive hereditary disorder characterized by isolated thrombocytopenia with small-sized platelets. The XLT locus has been located to chromosome Xp11 by linkage analysis, which is also where the recently cloned Wiskott-Aldrich syndrome (WAS) gene, maps. The relationship between XLT and WAS has long been debated; they might be due to different mutations of the same gene or to mutations in different genes. We now show that mutations in the WAS gene, different from those found in WAS patients, are present in three unrelated male patients with isolated thrombocytopenia and small-sized platelets. Our results demonstrate that XLT and WAS are allelic forms of the same disease, but the causes of the differences need to be further investigated.

Wiskott-Aldrich syndrome: new molecular and biochemical insights

The Wiskott-Aldrich syndrome is an uncommon X-linked recessive disease characterized by eczema, thrombocytopenia, and immunodeficiency. The clinical features begin early in life and include recurrent infections, bleeding, and severe eczema. Unless the condition is treated by bone marrow transplantation, the prognosis of Wiskott-Aldrich syndrome is grave, and premature death caused by sepsis, hemorrhage, or lymphoreticular malignancy is common. Although the biochemical defect responsible for the syndrome is not known, recent investigations with restriction fragment length polymorphisms have mapped the Wiskott-Aldrich syndrome locus to the proximal portion of the short arm of the human X chromosome (Xp11). The isolation of these DNA markers makes feasible both carrier detection and prenatal diagnosis of Wiskott-Aldrich syndrome and provides an important adjunct to the management of Wiskott-Aldrich syndrome for patients and their families. These genetic data, in conjunction with the recent identification of a specific O-glycosylation defect in lymphocytes from patients with Wiskott-Aldrich syndrome, present an opportunity for the eventual isolation of the Wiskott-Aldrich syndrome gene and identification of the underlying cellular defect. We review the clinical and laboratory features of this syndrome and summarize the new molecular and biochemical approaches that can be used in diagnosis, genetic counseling, and treatment.