Ernest Beutler, MD and Carol West
Background: Gaucher disease results from the accumulation of glucosylceramide (glucocerebroside) in tissues of affected persons. Patients sharing the same genotype present with widely varying degrees of lipid storage and of clinical manifestations.
Objectives: To determine whether variation in the glucosylceramide synthase (UDPGlucose ceramide glucosyltransferase) gene, which encodes the enzyme that regulates the synthesis of glucocerebroside, could account for the variability and clinical manifestations.
Methods: Patients homozygous for the 1226G (N370S) mutation, the most common in the Ashkenazi Jewish population, were investigated. The exons and flanking sequences of the gene were sequenced using DNA derived from five very mild Gaucher disease patients and four patients with relatively severe Gaucher disease. Results: One polymorphism was found in the coding region, but this did not change any amino acids. Seven other polymorphisms were found in introns and in the 5' untranslated region. Some of these were single nucleotide polymorphisms; others were insertions. The mutations appear to be in linkage equilibrium and none were found with a significantly higher frequency in either severe or mildly affected individuals.
Conclusions: Mutations in the glucosylceramide synthase gene do not appear to count for the variability in expression of the common Jewish Gaucher disease mutation.
David G. Motto, MD, PhD, James A. Williams, MD and Laurence A. Boxer, MD
Background: Chronic childhood autoimmune hemolytic anemia is an uncommon disorder that is associated with significant morbidity. Treatment with high dose steroids, splenectomy and frequent blood transfusions results in a myriad of complications including growth failure, bone demineralization, Cushing’s syndrome, immunosuppression, and transfusional hemosiderosis.
Objectives: To investigate the efficacy of the monoclonal anti-CD20 antibody, rituximab, in treating children with AIHA.
Methods: Four children with chronic AIHA, including two with prior splenectomy, who were dependent on high dose steroids and refractory to other immunosuppressive regimens were treated with four to six weekly doses of rituximab at a dose of 375 mg/m2.
Results: All four patients became transfusion-independent and were taken off prednisone completely. Adverse effects included infusion-related reactions that were mild, and infectious complications of Pneumocystis carinii pneumonia and varicella pneumonia.
Conclusions: Treatment with rituximab appears promising for refractory AIHA; it may obviate the need for prednisone and may result in sustained disease remissions in some patients.
by Melvin H. Freedman, MD, FAAP, FRCPC and Blanche P. Alter, MD, FAAP, MPH
Background: Granulocyte colony-stimulating factor has had a major impact on the management of severe chronic neutropenia – a collective term referring to congenital, idiopathic, or cyclic neutropenia. Almost all patients respond to G-CSF with increased neutrophils, reduced infections, and improved survival. Some responders with congenital neutropenia (termed Kostmann’s syndrome herein) and Shwachman-Diamond syndrome have developed myelodysplastic syndrome and acute myeloid leukemia, which raises the question of the role of G-CSF in pathogenesis. The issue is complicated because both disorders have a propensity for MDS or AML as part of their natural history.
Objective and Methods: To address this, the Severe Chronic Neutropenia International Registry used its large database of chronic neutropenia patients treated with G-CSF to determine the incidence of malignant myeloid transformation in the two disorders, and its relationship to treatment and to other patient characteristics.
Results: As of January 2001, of the 383 patients with congenital forms of neutropenia in the Registry, 48 had MDS or AML (crude rate, about 12.5%). No statistically significant relationships were found between age at onset of MDS or AML and patient gender, G-CSF dose, or duration of G-CSF therapy. What was observed, however, was the multistep acquisition of aberrant cellular genetic changes in marrow cells from Kostmann’s syndrome patients who transformed, including activating ras oncogene mutations, clonal cytogenetic abnormalities, and G-CSF receptor mutations. The latter in murine models produces a hyperproliferative response to G-CSF, confers resistance to apoptosis, and enhances cell survival.
Conclusions: Since Kostmann’s syndrome and Shwachman-Diamond syndrome are inherited forms of bone marrow failure, G-CSF may accelerate the propensity for MDS/AML in the genetically altered stem and progenitor cells, especially in those with G-CSF receptor and ras mutations (82% and 50% of Kostmann’s syndrome patients who transform, respectively). Alternatively, and equally plausible, G-CSF may simply be an innocent bystander that corrects neutropenia, prolongs patient survival, and allows time for the malignant predisposition to declare itself. Only careful long-term follow-up of the cohort of patients receiving G-CSF will provide the answer.
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G-CSF = granulocyte colony-stimulating factor
MDS = myelodysplastic syndrome
AML = acute myeloid leukemia
Shifra Sela, PhD, Revital Shurtz-Swirski, PhD, Jamal Awad, MD, Galina Shapiro, MSc, Lubna Nasser, MSc, Shaul M. Shasha, MD and Batya Kristal, MD
Background: Cigarette smoking is a well-known risk factor for the development of endothelial dysfunction and the progression of atherosclerosis. Oxidative stress and inflammation have recently been implicated in endothelial dysfunction.
Objectives: To assess the concomitant contribution of polymorphonuclear leukocytes to systemic oxidative stress and inflammation in cigarette smokers.
Methods: The study group comprised 41 chronic cigarette-smoking, otherwise healthy males aged 45.0 ± 11.5 (range 31–67 years) and 41 male non-smokers aged 42.6 ± 11.3 (range 31–65) who served as the control group. The potential generation of oxidative stress was assessed by measuring the rate of superoxide release from separated, phorbol 12-myristate 13-acetate-stimulated PMNL and by plasma levels of reduced (GSH) and oxidized (GSSG) glutathione. Inflammation was estimated indirectly by: a) determining the in vitro survival of PMNL, reflecting cell necrosis; b) in vivo peripheral PMNL counts, reflecting cell recruitment; and c) plasma alkaline phosphatase levels, indicating PMNL activation and degranulation.
Results: PMA-stimulated PMNL from cigarette smokers released superoxide at a faster rate than PMNL from the controls. Smokers had decreased plasma GSH and elevated GSSG levels. In vitro incubation of control and smokers' PMNL in sera of smokers caused necrosis, while control sera improved smoker PMNL survival. Smokers' PMNL counts, although in the normal range, were significantly higher than those of controls. Plasma ALP levels in smokers were significantly higher than in controls and correlated positively with superoxide release and PMNL counts.
Conclusions: Our study shows that PMNL in smokers are primed in vivo, contributing concomitantly to systemic oxidative stress and inflammation that predispose smokers to endothelial dysfunction, and explains in part the accelerated atherosclerosis found in smokers.
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PMNL = polymorphonuclear leukocytes
PMA = phorbol 12-myristate 13-acetate
GSH = reduced glutathione
GSSG = oxidized glutathione
ALP = alkaline phosphatase
Htwe. M. Zaw, MBBS, MRCS, Ian. C. Osborne, MBBS, Philip. N. Pettit, MBBS, MRCS, and Alexander. T. Cohen, MBBS, MSc, MD, FRACP
Pesach. J. Shteper, MSc and Dina Ben-Yehuda, MD
Jacob Cohen, MSc, Lia Supino-Rosin, MSc, Eran Barzilay, BSc, Ronit Eisen-Lev, DMD, Moshe Mittelman, MD and Drorit Neumann, PhD