Splenectomy and/or bone marrow transplantation in the management of the Wiskott-Aldrich syndrome: long-term follow-up of 62 cases

This study describes the effects of two major treatment options, splenectomy and/or bone marrow transplantation, on the natural history of the Wiskott-Aldrich (WAS) syndrome. The records of 62 patients with the WAS evaluated at the National Institutes of Health Clinical Center from 1966 to 1992 were reviewed. Nineteen patients were treated with bone marrow transplantation (BMT) and the results were largely dependent on the source of the graft. Twelve of 12 patients receiving HLA-matched sibling marrow achieved satisfactory immunologic and hematologic reconstitution. By contrast, only 2 of 7 patients receiving haploidentical, parental, or matched unrelated marrow survived more than 1 year after BMT. Thirty-nine patients who lacked suitable bone marrow donors early in their course underwent splenectomy for management of their thrombocytopenia; most received prophylactic antibiotics to minimize the risk of sepsis. Nearly all these patients achieved normal platelet counts and the rate of serious bleeding was reduced nearly sevenfold. Median survival in the untransplanted splenectomy group was 25 years, compared with less than 5 years in unsplenectomized patients. We conclude that HLA-matched sibling donor BMT is the treatment of choice for patients with WAS and that splenectomy and daily prophylactic antibiotics provide a significant survival advantage to those boys without a matched sibling donor. Splenectomy should probably be used in preference to unmatched BMT until results with alternative donor BMT significantly improve or gene therapy becomes available.     

Structure and function of the Wiskott-Aldrich syndrome protein

PURPOSE OF REVIEW: Mutations of the Wiskott-Aldrich syndrome protein can result in highly variable clinical symptoms that affect the hematopoietic/immunologic system. The responsible gene, WASP, has multiple domains, each with unique functions that were only recently fully recognized. RECENT FINDINGS: Two new comprehensive studies of patients with mutations of the Wiskott-Aldrich syndrome protein unequivocally demonstrated a strong phenotype-genotype correlation; the most predictive variable was the presence or absence of the Wiskott-Aldrich syndrome protein in the lymphoid cells from patients with X-linked thrombocytopenia or Wiskott-Aldrich syndrome, respectively. A third clinical study revealed a high rate (>70%) of autoimmune disorders in patients with classic Wiskott-Aldrich syndrome, possibly caused by immune dysregulation involving both T and B cell defects. In addition, the Wiskott-Aldrich syndrome protein is required for natural killer cell function by participating in the formation of immunologic synapses and facilitating the nuclear translocation of nuclear factor for activated T cell and nuclear factor-kappaB. Finally, the Wiskott-Aldrich syndrome protein was shown to play an important role in lymphoid development and in the maturation and function of myelomonocytic cells. SUMMARY: The progress made in dissecting the functions of the Wiskott-Aldrich syndrome protein has direct implications for our understanding of the distinct clinical phenotypes (Wiskott-Aldrich syndrome/X-linked thrombocytopenia; intermittent thrombocytopenia; congenital neutropenia), for making diagnostic and prognostic decisions, and for the selection of therapeutic strategies--from conservative symptomatic treatment to curative hematopoietic stem cell transplantation, or, in the future, gene therapy.     

Wiskott-aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency characterized by thrombocytopenia with small platelets, eczema, recurrent infections, autoimmune disorders, IgA nephropathy, and an increased incidence of hematopoietic malignancies. The identification of the responsible gene, WASP (Wiskott-Aldrich Syndrome Protein), revealed clinical heterogeneity of the syndrome, and showed that X-linked thrombocytopenia without, or with only mild immunodeficiency and eczema, is also caused by mutations of WASP. The study of WASP and its mutations demonstrates how a single gene defect can cause multiple and complex clinical symptoms.     

X-linked thrombocytopenia and Wiskott-Aldrich syndrome: similar regional assignment but distinct X-inactivation pattern in carriers

While inherited X-linked (XL) isolated thrombocytopenia is a mild condition, the Wiskott-Aldrich syndrome (WAS) associates severe thrombocytopenia with an immunodeficiency component and has a poor prognosis. Whether these conditions correspond to separate genetic entities or to different mutations of the same gene(s) remains unresolved. The Wiskott-Aldrich syndrome locus has been assigned to Xp 11.2 by means of RFLP studies. The X-inactivation pattern in female carriers has been found to follow a skewed pattern in the hematopoietic cells, thus allowing carrier detection. We studied a family with four members affected by XL thrombocytopenia and report the results of genetic segregation analysis, together with the X-inactivation pattern of hematopoietic cells from an obligate female carrier. Although the affected locus mapped to the same region as that of WAS, lymphocytes presented a skewed pattern of X-inactivation, whereas polymorphonuclear lymphocytes (PMN) did not. These results provide further evidence that the Wiskott-Aldrich syndrome and XL thrombocytopenia are different expressions of mutations within a single locus and that the severity of the disease corresponds to distinct hematopoietic cell selections in obligate carriers.     

Wiskott-Aldrich syndrome

PURPOSE OF REVIEW: Wiskott-Aldrich syndrome is caused by mutations of the Wiskott-Aldrich syndrome protein gene, which codes for a cytoplasmic protein with multiple functions. This review will focus on recent progress in understanding the molecular basis of Wiskott-Aldrich syndrome and its ramifications for the cure of this lethal disease. RECENT FINDINGS: The discovery of the causative gene has revealed a spectrum of clinical phenotypes demonstrating a strong genotype/phenotype correlation. The discovery of unique functional domains of Wiskott-Aldrich syndrome protein has been instrumental in defining mechanisms that control activation of Wiskott-Aldrich syndrome protein. Long-term follow up of patients undergoing hematopoietic stem cell transplantation has led to important modifications of the procedure. Studies of Wiskott-Aldrich syndrome protein-deficient cell lines and wasp-knockout mice have paved the way for possible gene therapy. SUMMARY: Wiskott-Aldrich syndrome protein gene mutations result in four clinical phenotypes: classic Wiskott-Aldrich syndrome and X-linked thrombocytopenia, intermittent thrombocytopenia and neutropenia. Wiskott-Aldrich syndrome protein is a signaling molecule and instrumental for cognate and innate immunity, cell motility and protection against autoimmune disease. The success of hematopoietic stem cell transplantation is related to the recipient's age, donor selection, the conditioning regimen and the extent of reconstitution. Since Wiskott-Aldrich syndrome protein is expressed exclusively in hematopoietic stem cells, and because Wiskott-Aldrich syndrome protein exerts a strong selective pressure, gene therapy is expected to cure the disease.     

Platelet-associated immunoglobulin, platelet size, and the effect of splenectomy in the Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) thrombocytopenia is frequently improved by splenectomy, although the mechanism of the thrombocytopenia and its resolution are unknown. Previous studies in two patients have shown that mean platelet volume, which is characteristically reduced in WAS, increased along with platelet count postsplenectomy. Additional studies in a limited number of patients have also demonstrated that platelet- associated immunoglobulin G (PAIgG) is elevated presplenectomy, but to date no postsplenectomy data have been reported. The present study was performed to more fully evaluate the effect of splenectomy on platelet volume and PAIgG in WAS. Before splenectomy, mean platelet volume was reduced but platelet size was broadly distributed with substantial overlap of the normal range. PAIgG was significantly elevated in 13 of 14 presplenectomy WAS patients (means = 78.9 fg per platelet) and fell to normal levels postoperatively (means = 4.0 fg per platelet). Platelet count and clinical status improved postsplenectomy, and mean platelet volume and platelet volume distribution returned to the normal range. WAS subjects who relapsed with recurrent thrombocytopenia redeveloped elevated PAIgG but maintained normal platelet size. The spleen appears to play a critical role in a process that may be immunologically mediated and results in reduced platelet size.     

Random X chromosome inactivation in a female with a variant of Wiskott-Aldrich syndrome

A 15-month-old female presented with eczema, thrombocytopenia, recurrent infections and failure to thrive. She had low serum IgM and IgG subclasses and an abnormal lymphocyte proliferative response to periodate in vitro. Molecular X chromosome inactivation analysis, using the polymorphic HUMARA DNA probe, showed that the infant has random X chromosome inactivation. We conclude that she has an atypical form of Wiskott-Aldrich syndrome which may be inherited in an autosomal recessive manner.     

Long-term treatment of refractory thrombocytopenia in a patient with Wiskott-Aldrich syndrome with vincristine, immunoglobulin, and methylprednisolone.

We report a child with Wiskott-Aldrich syndrome with severe, refractory, symptomatic thrombocytopenia who achieved an excellent response to combination therapy with vincristine 1.5 mg/m(2) x 1 day, intravenous immunoglobulin 1 g/kg x 3 days, and methylprednisolone 25 mg/kg x 3 days (VIM) for 7 years after failing multiple treatments. He did not have a histocompatible donor for bone marrow transplantation. When the patient ceased to respond to this regimen, he was rescued with pulse dexamethasone. Vincristine, immunoglobulin, and methylprednisolone might serve as a novel treatment option for the patient with refractory thrombocytopenia. Our patient had a sustained remission of symptomatic thrombocytopenia without toxicity. Furthermore, pulse dexamethasone might be an alternative treatment option to which patients with Wiskott-Aldrich syndrome may respond.     

Coincident Kaposi sarcoma and T-cell lymphoma in a patient with the Wiskott-Aldrich syndrome.

A 24 year old male with a history of eczema, recurrent mild infections, and thrombocytopenia consistent with the Wiskott-Aldrich syndrome (WAS) presented with a mediastinal mass, generalized lymphadenopathy, splenomegaly, and severe thrombocytopenia. Studies of immune function including immunoglobulin levels and T-cell subsets were normal. Furthermore, his T lymphocytes proliferated normally in response to phytohemagglutinin, concanavalin A, and the combination of neuraminidase/galactose oxidase. However, their proliferative responses to anti-CD43 antibody and periodate were diminished, consistent with the clinical diagnosis of WAS. An initial inguinal lymph node biopsy surprisingly revealed Kaposi sarcoma. However, following splenectomy to increase the platelet count, biopsy of the mediastinal mass revealed T-cell large cell lymphoma. Studies of biopsied tissue for the presence of Epstein-Barr virus and cytomegalovirus were negative, as were studies of blood, including the polymerase chain reaction, for the presence of the human immunodeficiency virus (HIV). This is the first report of Kaposi sarcoma arising in a patient with a congenital immunodeficiency syndrome. Although Kaposi sarcoma can arise in the face of the severe immunosuppression that follows allograft transplantation and in patients infected with HIV, we postulate that longevity in the face of mild immunosuppression was the major factor in the development of Kaposi sarcoma in this patient.     

Prophylactic platelet transfusion in children with thrombocytopenic disorders: a retrospective review

The safety of low platelet thresholds for prophylactic transfusions was retrospectively evaluated in 673 children with various thrombocytopenic disorders. In patients with idiopathic thrombocytopenic purpura and X linked thrombocytopenia the threshold for the use of platelet transfusion was based on bleeding events rather than platelet count. In children with hypoproliferative thrombocytopenia and Wiskott-Aldrich syndrome, prophylactic platelet transfusions were used when the platelet count was 10,000/microl in cases of bleeding or infections. The restrictive policy of platelet transfusions was shown to be proved safe in many thrombocytopenic disorders.     

Thrombotic risk in patients submitted to splenectomy for systemic lupus erythematosus and antiphospholipid antibody syndrome-related thrombocytopenia

Background: Splenectomy has been performed to treat refractory autoimmune thrombocytopenia. However, some reports have suggested that an increased risk of thrombosis could be present in splenectomized patients. This study aims to evaluate the possibility of an increased risk of thrombosis after splenectomy in patients with systemic lupus and antiphospholipid syndrome. Methods: Thrombotic-related events in patients with systemic lupus erythematosus (SLE) and/or primary antiphospholipid syndrome (PAPS), before and after splenectomy for severe thrombocytopenia, were compared. Clinical data, laboratory investigations, and anticoagulation or antiaggregation treatment data were collected from the notes of outpatients attending three European centers. Results: Twenty patients who had had a splenectomy were identified: eight with SLE, five with PAPS, and seven with SLE and APS. The mean time between diagnosis and splenectomy was 3.1 years and mean follow-up was 6.5 years. There were no differences in anticardiolipin antibody titers, lupus anticoagulant, anti-DNA or anti-nuclear antibodies before and after surgery. The incidence of venous events before and after splenectomy was not significantly different. There was a trend towards an increase in the total number of arterial events post-splenectomy. In aCL-positive patients, and in the pre-splenectomy period, the total number of miscarriages was higher (p=0.017), as was the number of patients who had had a miscarriage (p=0.025). Conclusions: The total risk of thrombosis in patients with PAPS and SLE was not increased after splenectomy, but there was a trend towards an increase in the number of arterial events. Splenectomy induced long-term remission of thrombocytopenia (partial or complete) in all patients.     

Long-term outcome following hematopoietic stem-cell transplantation in Wiskott-Aldrich syndrome: collaborative study of the European Society for Immunodeficiencies and European Group for Blood and Marrow Transplantation

Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency with microthrombocytopenia, eczema, recurrent infections, autoimmune disorders, and malignancies that are life-threatening in the majority of patients. In this long-term, retrospective, multicenter study, we analyzed events that occurred in 96 WAS patients who received transplants between 1979 and 2001 who survived at least 2 years following hematopoietic stem-cell transplantation (HSCT). Events included chronic graft-versus-host disease (cGVHD), autoimmunity, infections, and sequelae of before or after HSCT complications. Three patients (3%) died 2.1 to 21 years following HSCT. Overall 7-year event-free survival rate was 75%. It was lower in recipients of mismatched related donors, also in relation with an older age at HSCT and disease severity. The most striking finding was the observation of cGVHD-independent autoimmunity in 20% of patients strongly associated with a mixed/split chimerism status (P < .001), suggesting that residual-host lymphocytes can mediate autoimmune disease despite the coexistence of donor lymphocytes. Infectious complications (6%) related to splenectomy were also significant and may warrant a more restrictive approach to performing splenectomy in WAS patients. Overall, this study provides the basis for a prospective, standardized, and more in-depth detailed analysis of chimerism and events in long-term follow-up of WAS patients who receive transplants to design better-adapted therapeutic strategies.     

Thrombocytopenia in homosexual patients. Prognosis, response to therapy, and prevalence of antibody to the retrovirus associated with the acquired immunodeficiency syndrome

Thirty-three homosexual patients with thrombocytopenia (mean [+/- SE] platelet count, 50 000 +/- 7000/mm3; range, 7 to 135 000/mm3) have been followed for a mean period of 20 +/- 2 months. Six patients have developed the acquired immunodeficiency syndrome 1 to 37 months after the diagnosis of thrombocytopenia. Six patients spontaneously reverted to normal platelet counts 5 to 27 months (median, 10 months) after the diagnosis of thrombocytopenia, in the absence of splenectomy and while not receiving corticosteroids. Sixteen of seventeen patients had a moderate to excellent response while on corticosteroid treatment. Ten of ten patients had an excellent response to splenectomy which has persisted. Fifteen patients did not require treatment for their thrombocytopenia. Thirteen of fourteen patients had antibody against the retrovirus associated with the acquired immunodeficiency syndrome, as did 4 of 12 homosexual controls without thrombocytopenia. Thrombocytopenia in homosexuals is part of the complex related to the acquired immunodeficiency syndrome.     

"Idiopathic thrombocytopenic purpura-like syndrome" treated with interferon in a patient with lung cancer.

A case of autoimmune thrombocytopenia associated with lung cancer is presented. The thrombocytopenia occurred 2 years before the diagnosis of lung cancer. Previous treatments include high doses of corticosteroids and splenectomy. The patient was managed with interferon, which resulted in an increase of the platelet count with control of the hemorrhagic manifestations with this syndrome.     

Nonrandom inactivation of the X chromosome in early lineage hematopoietic cells in carriers of Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is an X-linked (Xp11.22) recessive immunodeficiency syndrome characterized by susceptibility to opportunistic and pyogenic infections, thrombocytopenia, and eczema. Previous studies of obligate carriers of WAS documented that nonrandom inactivation of the X chromosome carrying the defective gene is observed in all peripheral blood cells. The existence of both abnormal platelets and lymphocytes is consistent with a defect that affects early hematopoietic precursors. We isolated CD34+ hematopoietic progenitor cells collected from obligate carriers of WAS by apheresis and used polymerase chain reaction analysis of a polymorphic variable number of repeats (VNTR) within the X-linked androgen receptor to document nonrandom inactivation. These data show that nonrandom inactivation of the X-chromosome in WAS-obligate carriers occurs early during hematopoietic differentiation.     

Partial splenic embolization.

Partial splenic embolization (PSE) is a non-surgical procedure developed to treat hypersplenism as a result of hepatic disease and thus avoid the disadvantages of splenectomy. A femoral artery approach is used for selective catheterization of the splenic artery. Generally, the catheter tip is placed as distally as possible in an intrasplenic artery. After an injection of antibiotics and steroids, embolization is achieved by injecting 2-mm gelatin sponge cubes suspended in a saline solution containing antibiotics. PSE can benefit patients with thrombocytopenia, esophagogastric varices, portal hypertensive gastropathy, encephalopathy, liver dysfunction, splenic aneurysm, and splenic trauma. The contraindications of PSE include secondary splenomegaly and hypersplenism in patients with terminal-stage underlying disease; pyrexia or severe infections are associated with a high risk of splenic abscess after PSE. Complications of PSE include daily intermittent fever, abdominal pain, nausea and vomiting, abdominal fullness, appetite loss, and postembolization syndrome. Decreased portal-vein flow and a rapid increase in the platelet count after excessive embolization may cause portal-vein or splenic-vein thrombosis.     

Deficiency in the Wiskott-Aldrich protein induces premature proplatelet formation and platelet production in the bone marrow compartment

The pathophysiology of microthrombocytopenia in the Wiskott-Aldrich syndrome (WAS) and its milder form, X-linked thrombocytopenia (XLT), is unclear. Although quantitative defects are correctable by splenectomy, residual platelet abnormalities are suggestive of intrinsic disturbances of production. In contrast to human patients, murine models of WASp deficiency exhibit only mild thrombocytopenia, and platelets are of normal size. Here, we have identified a critical role for WASp during murine platelet biogenesis. By electron microscopy, WASp-deficient MKs appeared to have shed platelets ectopically within the bone marrow space. WASp-deficient megakaryocytes (MKs) also displayed defects in response to fibrillar collagen I (CI) in vitro, the major matrix component of bone. These included a loss of normal CI receptor (alpha2beta1 integrin)-mediated inhibition of proplatelet formation, a marked abrogation of SDF-1-induced chemotactic migration of CD41+ MKs adherent to CI, and an almost complete lack of actin-rich podosomes, normally induced by interaction between CI and its receptors GPVI or alpha2beta1 integrin. These findings highlight the central and highly specialized role of WASp in MKs during platelet biogenesis, and may provide a mechanism for the mild thrombocytopenia observed in WASp-deficient mice. In addition, they suggest a novel explanation for some of the platelet abnormalities characteristic of patients with WAS.     

Recurrent V75M mutation within the Wiskott-Aldrich syndrome protein: description of a homozygous female patient

The Wiskott-Aldrich syndrome is a rare genetic disorder due to mutations in the WAS gene situated on chromosome X. It is comprised of microthrombocytopenia, eczema and immunodeficiency. However, the phenotypical presentation may vary as to the number and intensity of its manifestations. A milder form of Wiskott-Aldrich syndrome is known as the X-linked thrombocytopenia. We independently found eight individual or familial cases with the V75M substitution (9.76%). This high incidence was partly accounted for by the fact that three cases turned out to be related. The V75M mutation is recurrent, however, due to a CpG island. A genuine homozygous female patient was found. She showed microthrombocytopenia and infections to the same degree as her hemizygous father and brother. The WAS protein was decreased in a comparable fashion in the hemizygotes and the homozygote as well. Its amount was about 10% and 15% of normal in platelets and mononucleated white cells, respectively. In all patients was the picture consistent with XLT.     

Prolonged remission after splenectomy for refractory Evans syndrome--a case report and literature review

We describe a patient with Evans syndrome (autoimmune hemolytic anemia and autoimmune thrombocytopenia) who was refractory to steroids and intravenous immunoglobulin. She responded to splenectomy and has remained in clinical remission for 3 years. In the majority of cases, splenectomy rarely induces a durable remission but it may be beneficial in a small group of patients, hence should be considered as alternative therapy in the management of these patients.