Bendamustine lymphodepletion before axicabtagene ciloleucel is safe and associates with reduced inflammatory cytokines

ABSTRACT

Lymphodepletion (LD) is an integral component of chimeric antigen receptor T-cell (CART) immunotherapies. In this study, we compared the safety and efficacy of bendamustine (Benda) to standard fludarabine/cyclophosphamide (Flu/Cy) LD before CD19-directed, CD28-costimulated CART axicabtagene ciloleucel (axi-cel) for patients with large B-cell lymphoma (LBCL) and follicular lymphoma (FL). We analyzed 59 patients diagnosed with LBCL (n = 48) and FL (n = 11) consecutively treated with axi-cel at the University of Pennsylvania. We also analyzed serum samples for cytokine levels and metabolomic changes before and after LD. Flu/Cy and Benda demonstrated similar efficacy, with complete remission rates of 51.4% and 50.0% (P = .981), respectively, and similar progression-free and overall survivals. Any-grade cytokine-release syndrome occurred in 91.9% of patients receiving Flu/Cy vs 72.7% of patients receiving Benda (P = .048); any-grade neurotoxicity after Flu/Cy occurred in 45.9% of patients and after Benda in 18.2% of patients (P = .031). In addition, Flu/Cy was associated with a higher incidence of grade ≥3 neutropenia (100% vs 54.5%; P < .001), infections (78.4% vs 27.3%; P < .001), and neutropenic fever (78.4% vs 13.6%; P < .001). These results were confirmed both in patients with LBCL and those with FL. Mechanistically, patients with Flu/Cy had a greater increase in inflammatory cytokines associated with neurotoxicity and reduced levels of metabolites critical for redox balance and biosynthesis. This study suggests that Benda LD may be a safe alternative to Flu/Cy for CD28-based CART CD19-directed immunotherapy with similar efficacy and reduced toxicities. Benda is associated with reduced levels of inflammatory cytokines and increased anabolic metabolites.

The proteasome regulator PSME4 modulates proteasome activity and antigen diversity to abrogate antitumor immunity in NSCLC

Immunotherapy revolutionized treatment options in cancer, yet the mechanisms underlying resistance in many patients remain poorly understood. Cellular proteasomes have been implicated in modulating antitumor immunity by regulating antigen processing, antigen presentation, inflammatory signaling and immune cell activation. However, whether and how proteasome complex heterogeneity may affect tumor progression and the response to immunotherapy has not been systematically examined. Here, we show that proteasome complex composition varies substantially across cancers and impacts tumor-immune interactions and the tumor microenvironment. Through profiling of the degradation landscape of patient-derived non-small-cell lung carcinoma samples, we find that the proteasome regulator PSME4 is upregulated in tumors, alters proteasome activity, attenuates presented antigenic diversity and associates with lack of response to immunotherapy. Collectively, our approach affords a paradigm by which proteasome composition heterogeneity and function should be examined across cancer types and targeted in the context of precision oncology.

Increased tumor glycolysis is associated with decreased immune infiltration across human solid tumors

Response to immunotherapy across multiple cancer types is approximately 25%, with some tumor types showing increased response rates compared to others (i.e. response rates in melanoma and non-small cell lung cancer (NSCLC) are typically 30-60%). Patients whose tumors are resistant to immunotherapy often lack high levels of pre-existing inflammation in the tumor microenvironment. Increased tumor glycolysis, acting through glucose deprivation and lactic acid accumulation, has been shown to have pleiotropic immune suppressive effects using in-vitro and in-vivo models of disease. To determine whether the immune suppressive effect of tumor glycolysis is observed across human solid tumors, we analyzed glycolytic and immune gene expression patterns in multiple solid malignancies. We found that increased expression of a glycolytic signature was associated with decreased immune infiltration and a more aggressive disease across multiple tumor types. Radiologic and pathologic analysis of untreated estrogen receptor (ER)-negative breast cancers corroborated these observations, and demonstrated that protein expression of glycolytic enzymes correlates positively with glucose uptake and negatively with infiltration of CD3⁺ and CD8⁺ lymphocytes. This study reveals an inverse relationship between tumor glycolysis and immune infiltration in a large cohort of multiple solid tumor types.

Genetic and Drug Inhibition of LDH-A: Effects on Murine Gliomas

The effects of the LDH-A depletion via shRNA knockdown on three murine glioma cell lines and corresponding intracranial (i.c.) tumors were studied and compared to pharmacologic (GNE-R-140) inhibition of the LDH enzyme complex, and to shRNA scrambled control (NC) cell lines. The effects of genetic-shRNA LDH-A knockdown and LDH drug-targeted inhibition (GNE-R-140) on tumor-cell metabolism, tumor growth, and animal survival were similar. LDH-A KD and GNE-R-140 unexpectedly increased the aggressiveness of GL261 intracranial gliomas, but not CT2A and ALTS1C1 i.c. gliomas. Furthermore, the bioenergetic profiles (ECAR and OCR) of GL261 NC and LDH-A KD cells under different nutrient limitations showed that (a) exogenous pyruvate is not a major carbon source for metabolism through the TCA cycle of native GL261 cells; and (b) the unique upregulation of LDH-B that occurs in GL261 LDH-A KD cells results in these cells being better able to: (i) metabolize lactate as a primary carbon source through the TCA cycle, (ii) be a net consumer of lactate, and (iii) showed a significant increase in the proliferation rate following the addition of 10 mM lactate to the glucose-free media (only seen in GL261 KD cells). Our study suggests that inhibition of LDH-A/glycolysis may not be a general strategy to inhibit the i.c. growth of all gliomas, since the level of LDH-A expression and its interplay with LDH-B can lead to complex metabolic interactions between tumor cells and their environment. Metabolic-inhibition treatment strategies need to be carefully assessed, since the inhibition of glycolysis (e.g., inhibition of LDH-A) may lead to the unexpected development and activation of alternative metabolic pathways (e.g., upregulation of lipid metabolism and fatty-acid oxidation pathways), resulting in enhanced tumor-cell survival in a nutrient-limited environment and leading to increased tumor aggressiveness.

LDH-A—Modulation and the Variability of LDH Isoenzyme Profiles in Murine Gliomas: A Link with Metabolic and Growth Responses

Three murine glioma cell lines (GL261, CT2A, and ALTS1C1) were modified to downregulate the expression of the murine LDH-A gene using shRNA, and compared to shRNA scrambled control (NC) cell lines. Differences in the expression of LDH-A and LDH-B mRNA, protein and enzymatic activity, as well as their LDH isoenzyme profiles, were observed in the six cell lines, and confirmed successful LDH-A KD. LDH-A KD (knock-down) resulted in metabolic changes in cells with a reduction in glycolysis (GlycoPER) and an increase in basal respiratory rate (mitoOCR). GL261 cells had a more limited ATP production capacity compared to CT2A and ALTS1C1 cells. An analysis of mRNA expression data indicated that: (i) GL261 LDH-A KD cells may have an improved ability to metabolize lactate into the TCA cycle; and (ii) that GL261 LDH-A KD cells can upregulate lipid metabolism/fatty acid oxidation pathways, whereas the other glioma cell lines do not have this capacity. These two observations suggest that GL261 LDH-A KD cells can develop/activate alternative metabolic pathways for enhanced survival in a nutrient-limited environment, and that specific nutrient limitations have a variable impact on tumor cell metabolism and proliferation. The phenotypic effects of LDH-A KD were compared to those in control (NC) cells and tumors. LDH-A KD prolonged the doubling time of GL261 cells in culture and prevented the formation of subcutaneous flank tumors in immune-competent C57BL/6 mice, whereas GL261 NC tumors had a prolonged growth delay in C57BL/6 mice. In nude mice, both LDH-A KD and NC GL261 tumors grew rapidly (more rapidly than GL261 NC tumors in C57BL/6 mice), demonstrating the impact of an intact immune system on GL261 tumor growth. No differences between NC and KD cell proliferation (in vitro) or tumor growth in C57BL/6 mice (doubling time) were observed for CT2A and ALTS1C1 cells and tumors, despite the small changes to their LDH isoenzyme profiles. These results suggest that GL261 glioma cells (but not CT2A and ALTS1C1 cells) are pre-programmed to have the capacity for activating different metabolic pathways with higher TCA cycle activity, and that this capacity is enhanced by LDH-A depletion. We observed that the combined impact of LDH-A depletion and the immune system had a significant impact on the growth of subcutaneous-located GL261 tumors.

CTLA-4 blockade drives loss of Treg stability in glycolysis-low tumours

Limiting the metabolic competition in the tumor microenvironment (TME) may increase the effectiveness of immunotherapy. Because of its critical role in glucose metabolism of activated T cells, CD28 signaling has been proposed as a T-cell metabolic biosensor¹. Conversely, CTLA-4 engagement has been shown to down-regulate T-cell glycolysis¹. Here, we investigated the impact of CTLA-4 blockade on the metabolic fitness of intra-tumor T cells in relationship to the tumor glycolytic capacity. We found that CTLA-4 blockade promotes immune cell infiltration and metabolic fitness especially in glycolysis-low tumors. Accordingly, anti-CTLA-4 achieved better therapeutic outcomes in mice bearing glycolysis-defective tumors. Intriguingly, tumor-specific CD8⁺ T-cell responses correlated with phenotypic and functional destabilization of tumor-infiltrating regulatory T cells (Tregs) toward IFN-γ- and TNF-α-producing cells in glycolysis-defective tumors. By mimicking the highly and poorly glycolytic TME in vitro, we show that the effect of CTLA-4 blockade to promote Treg destabilization is dependent on Treg glycolysis and CD28 signaling. These findings indicate that decreasing tumor competition for glucose may facilitate the therapeutic activity of CTLA-4 blockade, thus supporting its combination with inhibitors of tumor glycolysis. Moreover, these results reveal a new mechanism through which anti-CTLA-4 interferes with Treg function in the presence of glucose.

Lactate Dehydrogenase A Depletion Alters MyC-CaP Tumor Metabolism, Microenvironment, and CAR T Cell Therapy

To enhance human prostate-specific membrane antigen (hPSMA)-specific chimeric antigen receptor (CAR) T cell therapy in a hPSMA⁺ MyC-CaP tumor model, we studied and imaged the effect of lactate dehydrogenase A (LDH-A) depletion on the tumor microenvironment (TME) and tumor progression. Effective LDH-A short hairpin RNA (shRNA) knockdown (KD) was achieved in MyC-CaP:hPSMA⁺ Renilla luciferase (RLuc)-internal ribosome entry site (IRES)-GFP tumor cells, and changes in tumor cell metabolism and in the TME were monitored. LDH-A downregulation significantly inhibited cell proliferation and subcutaneous tumor growth compared to control cells and tumors. However, total tumor lactate concentration did not differ significantly between LDH-A knockdown and control tumors, reflecting the lower vascularity, blood flow, and clearance of lactate from LDH-A knockdown tumors. Comparing treatment responses of MyC-CaP tumors with LDH-A depletion and/or anti-hPSMA CAR T cells showed that the dominant effect on tumor growth was LDH-A depletion. With anti-hPSMA CAR T cell treatment, tumor growth was significantly slower when combined with tumor LDH-A depletion and compared to control tumor growth (p < 0.0001). The lack of a complete tumor response in our animal model can be explained in part by (1) the lower activity of human CAR T cells against hPSMA-expressing murine tumors in a murine host, and (2) a loss of hPSMA antigen from the tumor cell surface in progressive generations of tumor cells.

Gold/alpha-lactalbumin nanoprobes for the imaging and treatment of breast cancer

Theranostic agents should ideally be renally cleared and biodegradable. Here, we report the synthesis, characterization and theranostic applications of fluorescent ultrasmall gold quantum clusters that are stabilized by the milk metalloprotein alpha-lactalbumin. We synthesized three types of these nanoprobes that together display fluorescence across the visible and near-infrared spectra when excited at a single wavelength through optical colour coding. In live tumour-bearing mice, the near-infrared nanoprobe generates contrast for fluorescence, X-ray computed tomography and magnetic resonance imaging, and exhibits long circulation times, low accumulation in the reticuloendothelial system, sustained tumour retention, insignificant toxicity and renal clearance. An intravenously administrated near-infrared nanoprobe with a large Stokes shift facilitated the detection and image-guided resection of breast tumours in vivo using a smartphone with modified optics. Moreover, the partially unfolded structure of alpha-lactalbumin in the nanoprobe helps with the formation of an anti-cancer lipoprotein complex with oleic acid that triggers the inhibition of the MAPK and PI3K-AKT pathways, immunogenic cell death and the recruitment of infiltrating macrophages. The biodegradability and safety profile of the nanoprobes make them suitable for the systemic detection and localized treatment of cancer.

LDH-A regulates the tumor microenvironment via HIF-signaling and modulates the immune response

Previous studies show that LDH-A knockdown reduces orthotopic 4T1 breast tumor lactate and delays tumor growth and the development of metastases in nude mice. Here, we report significant changes in the tumor microenvironment (TME) and a more robust anti-tumor response in immune competent BALB/c mice. 4T1 murine breast cancer cells were transfected with shRNA plasmids directed against LDH-A (KD) or a scrambled control plasmid (NC). Cells were also transduced with dual luciferase-based reporter systems to monitor HIF-1 activity and the development of metastases by bioluminescence imaging, using HRE-sensitive and constitutive promoters, respectively. The growth and metastatic profile of orthotopic 4T1 tumors developed from these cell lines were compared and a primary tumor resection model was studied to simulate the clinical management of breast cancer. Primary tumor growth, metastasis formation and TME phenotype were significantly different in LDH-A KD tumors compared with controls. In LDH-A KD cells, HIF-1 activity, hexokinase 1 and 2 expression and VEGF secretion were reduced. Differences in the TME included lower HIF-1α expression that correlated with lower vascularity and pimonidazole staining, higher infiltration of CD3⁺ and CD4⁺ T cells and less infiltration of TAMs. These changes resulted in a greater delay in metastases formation and 40% long-term survivors (>20 weeks) in the LDH-A KD cohort following surgical resection of the primary tumor. We show for the first time that LDH-depletion inhibits the formation of metastases and prolongs survival of mice through changes in tumor microenvironment that modulate the immune response. We attribute these effects to diminished HIF-1 activity, vascularization, necrosis formation and immune suppression in immune competent animals. Gene-expression analyses from four human breast cancer datasets are consistent with these results, and further demonstrate the link between glycolysis and immune suppression in breast cancer.

Autogenous and efficient acceleration of energetic ions upstream of Earth's bow shock

Earth and its magnetosphere are immersed in the supersonic flow of the solar-wind plasma that fills interplanetary space. As the solar wind slows and deflects to flow around Earth, or any other obstacle, a 'bow shock' forms within the flow. Under almost all solar-wind conditions, planetary bow shocks such as Earth's are collisionless, supercritical shocks, meaning that they reflect and accelerate a fraction of the incident solar-wind ions as an energy dissipation mechanism^1,2, which results in the formation of a region called the ion foreshock³. In the foreshock, large-scale, transient phenomena can develop, such as 'hot flow anomalies'^4-9, which are concentrations of shock-reflected, suprathermal ions that are channelled and accumulated along certain structures in the upstream magnetic field. Hot flow anomalies evolve explosively, often resulting in the formation of new shocks along their upstream edges^5,10, and potentially contribute to particle acceleration^11-13, but there have hitherto been no observations to constrain this acceleration or to confirm the underlying mechanism. Here we report observations of a hot flow anomaly accelerating solar-wind ions from roughly 1-10 kiloelectronvolts up to almost 1,000 kiloelectronvolts. The acceleration mechanism depends on the mass and charge state of the ions and is consistent with first-order Fermi acceleration^14,15. The acceleration that we observe results from only the interaction of Earth's bow shock with the solar wind, but produces a much, much larger number of energetic particles compared to what would typically be produced in the foreshock from acceleration at the bow shock. Such autogenous and efficient acceleration at quasi-parallel bow shocks (the normal direction of which are within about 45 degrees of the interplanetary magnetic field direction) provides a potential solution to Fermi's 'injection problem', which requires an as-yet-unexplained seed population of energetic particles, and implies that foreshock transients may be important in the generation of cosmic rays at astrophysical shocks throughout the cosmos.

Impact of the Tumor Microenvironment on Tumor-Infiltrating Lymphocytes: Focus on Breast Cancer

Immunotherapy is revolutionizing cancer care across disciplines. The original success of immune checkpoint blockade in melanoma has already been translated to Food and Drug Administration-approved therapies in a number of other cancers, and a large number of clinical trials are underway in many other disease types, including breast cancer. Here, we review the basic requirements for a successful antitumor immune response, with a focus on the metabolic and physical barriers encountered by lymphocytes entering breast tumors. We also review recent clinical trials of immunotherapy in breast cancer and provide a number of interesting questions that will need to be answered for successful breast cancer immunotherapy.

Electron-scale measurements of magnetic reconnection in space

Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth's magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy; (ii) measured the electric field and current, which together cause the dissipation of magnetic energy; and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region.

Antiangiogenic therapy and surgical practice (Br J Surg 2008; 95: 281–293)

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses should be sent electronically via the BJS website (www.bjs.co.uk). All letters will be reviewed and, if approved,appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length.

Ewing Sarcoma tumor cells express CD34: implications for autologous stem cell transplantation

The significance of tumor cell contamination in marrow and peripheral blood stem cell (PBSC) collections of patients with solid tumors remains controversial. Various methods have been developed to purge tumor cells from autologous stem cell products, including CD34+ selection. PBSC harvests from patients with Ewing family of tumors (EFT) were analyzed for contaminating tumor cells prior and after CD34+ selection using reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry (FC) analyzes. The expression of CD34 was studied by RT-PCR and FC in 14 primary tumors and 13 PBSC harvests, respectively. Tumor cells were identified in the harvests by both methods. In two patients, contaminating tumor cells were evident by RT-PCR only after positive selection. FC analysis confirmed a higher level of tumor cells in the CD34+ fraction. In an attempt to explore this finding, expression of CD34 was detected in 93% of primary tumors and 67% of contaminated harvests. As CD34 is expressed on EFT cells, these cells may be enriched following CD34+ selection of harvests, although the total number of tumor cells is reduced. Other methods of purging, rather than CD34+ selection, should be explored in patients with EFT undergoing autologous stem cell transplantation.

Tumor cells are present in stem cell harvests of Ewings sarcoma patients and their persistence following transplantation is associated with relapse

BACKGROUND

Tumor cells frequently contaminate autologous stem cell products in a variety of malignancies, but their clinical significance remains controversial. We retrospectively monitored tumor contamination in stem cell harvests from patients with Ewing family of tumors (EFT) all harboring the specific translocation EWS-FLI-1 that characterize these tumors.

PROCEDURE

Twenty- seven harvests from 11 patients were included in the study. In addition, 6 and 19 bone marrow (BM) or peripheral blood (PBL) samples were available before and after transplantation, respectively, for RT-PCR and nested PCR analyzes.

RESULTS

All 11 patients had contaminating tumor cells in their harvests. All samples prior to transplantation were RT-PCR positive. Two out of the 11 patients who underwent transplantation died of complications. Out of the remaining nine patients, two are alive and well 68 and 84 months from diagnosis, and are the only patients with no detectable tumor cells in their samples after transplantation. One of these patients harbored contaminating tumor cells in only one of the two harvests collected. Seven patients relapsed after transplant, and in four patients BM/PBL samples were available prior to the clinical relapse. All these samples harbored contaminating tumor cells.

CONCLUSIONS

We suggest a possible correlation between the amount of contaminating cells in the harvest and relapse after transplantation. Quantitative RT-PCR studies of the chimeric transcripts are underway to explore this issue.

Association Between Telomerase Activity and Outcome in Patients With Nonmetastatic Ewing Family of Tumors

Purpose: Telomerase is considered a molecular marker for malignancy. The aim of this study was to determine telomerase activity (TA) as a prognostic factor at diagnosis and as a marker for minimal residual disease during therapy and follow-up in nonmetastatic Ewing family of tumors (EFT).

Patients and Methods: Primary tumor specimens and 97 peripheral blood (PBL) samples from 31 EFT patients were analyzed for TA by the Telomeric Repeat Amplification Protocol (TRAP assay). The telomerase catalytic subunit (human telomerase reverse transcriptase [hTERT]) gene expression was evaluated by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and telomere length was determined by Southern blotting. The presence of the EFT chimeric transcripts was analyzed by RT-PCR. Correlations with progression-free survival were evaluated.

Results: At diagnosis, TA in primary tumors did not correlate with outcome. During therapy and follow-up, highly significant correlation was observed between high TA in PBL samples and adverse prognosis (P < .0001). None of the patients harboring low TA progressed, with a long follow-up (median, 60 months) and a progression-free survival (PFS) of 100%. In nine patients, high TA actually could predict relapse, long before overt clinical relapse. The group of patients with high TA and positive RT-PCR had the most adverse outcome; PFS of 20% (P = .0025). TA was found to be a better prognostic factor than RT-PCR and histopathologic response at surgery.

Conclusion: The results suggest that TA is a significant prognostic variable, superior to the established clinical prognostic parameters during therapy and tumor surveillance. It could be used in combination with RT-PCR for a new risk classification.

Molecular cytogenetic parameters in Ewing sarcoma

To evaluate possible genomic instability and possible random aneuploidy, we applied comparative genomic hybridization and fluorescence in situ techniques, and evaluated telomerase activity in 16 cases of Ewing sarcoma (EWS) and compared the results to 7 controls. Common secondary aberrations (gains of chromosomes 8 and 12) were found in the study group. There was a direct correlation between the detection of random aneuploidy and development of tumor relapse (P = 0.0047). Other detectable abnormal parameters (secondary) and high telomerase activity were also more common among the cases with relapse but did not reach a statistical significance (probably because of the small sample size). In EWS, the detection of random aneuploidy seems to be a sensitive parameter in the prediction of tumor relapse.

Treatment of alpha-fetoprotein secreting hepatoblastoma by response of serum alpha-fetoprotein levels: a new concept

Hepatoblastoma, the commonest primary malignant liver tumor in infants and children, is usually associated with elevated serum alpha-fetoprotein (AFP) levels. The authors sought to determine if AFP levels can be used to modify treatment, thereby avoiding the wait for formal imaging studies and prolonged suboptimal treatment and limiting the use of effective but toxic chemotherapy. From April 1984 to December 1997, 8 children were diagnosed with AFP-secreting hepatoblastoma. Serum AFP levels were measured weekly. If AFP levels failed to improve, or increased on at least 2 successive examinations, the chemotherapy protocol was changed. When an excellent response was achieved, less toxic chemotherapy was substituted. Six patients (75%) were disease-free for at least 2 years, some with high-risk or metastatic disease. Two patients died. Six of the 7 nonmetastatic patients (86%) remain disease-free (only one had a resectable tumor). Chemotherapy changes resulted in reduced AFP levels in 7 patients. This study supports the use of AFP monitoring to modify treatment in hepatoblastoma responding to therapy with less toxic drugs and the use of nonstandard therapy when suboptimal responses are obtained.

Optic pathway glioma: correlation of imaging findings with the presence of neurofibromatosis

BACKGROUND AND PURPOSE

Despite the benign histology of optic pathway glioma (OPG) (low-grade astrocytoma), its biological behavior is unpredictable, and it is unclear whether specific morphologic or anatomic patterns may be predictive of prognosis. It is also unclear whether OPG associated with neurofibromatosis (NF) is a distinct entity from non-NF-OPG. Our purpose was to describe the MR imaging features of OPG, compare the findings between patients with and those without NF, and identify prognostic imaging signs.

METHODS

MR examinations of 91 patients with OPG (47 with NF and 44 without) were reviewed at presentation and during follow-up. The images were evaluated for size and extension of tumor, and imaging parameters. Statistical bivariate analysis was used to compare the patients with and those without NF, and Pearson correlation was used to evaluate the correlation between the different imaging parameters and prognosis. Kappa values were calculated to determine intraobserver and interobserver variability.

RESULTS

The most common site of involvement in the NF group was the orbital nerve (66%), followed by the chiasm (62%). In the non-NF group, the chiasm was the most common site of involvement (91%); the orbital nerves were involved in only 32%. Extension beyond the optic pathway at diagnosis was uncommon in the NF group (2%) but frequent in the non-NF group (68%). In the NF group, the tumor was smaller and the original shape of the optic pathways was preserved (91% vs. 27% in the non-NF group). The presence of cystic components was significantly more common in the non-NF patients (66% vs. 9% in the NF group). During follow-up, half the NF patients remained stable, in contrast to 5% of the non-NF group. No statistical correlation was found between imaging features and biological behavior of the tumor.

CONCLUSION

NF-OPG is a separate entity from non-NF-OPG, with different imaging features and prognosis, thereby warranting a specific diagnostic, clinical, and therapeutic approach.

Effect of P-glycoprotein expression on outcome in the Ewing family of tumors

This study was designed to determine the prognostic significance of multidrug resistance, mediated by P-glycoprotein (Pgp) expression, in Ewing sarcoma. The clinical and laboratory features, treatment protocol, and outcome of 75 patients with Ewing sarcoma or peripheral neuroectodermal tumor treated between 1972 and 1997 were reviewed. Pgp expression was tested with the monoclonal antibody JSB-1. Thirty-four (64%) of the 53 tissue samples from untreated patients stained positive for Pgp. Progression-free and overall survival were 44 and 59%, respectively, in patients with negative findings, and 28 and 41% in those with positive findings; neither difference was significant. Of the 12 relapsed patients, 6 (50%) expressed more Pgp after chemotherapy than at diagnosis and 4 (33%) expressed less. Within these subgroups, 5 out of 6 and 3 out of 4 died from the disease. No correlation was found between Pgp and known prognostic factors of Ewing tumors. Pgp expression is probably an intrinsic factor of Ewing tumors but has no correlation to prognosis.

Visual pathway tumors and hydrocephalus

The authors evaluated the impact of hydrocephalus on the clinical picture of children with visual pathway tumor (VPT) with or without neurofibromatosis (NF). Charts of children with VPT treated in the authors' center since 1985 were retrospectively reviewed, and those with hydrocephalus were selected and summarized. Thirty-five children with VPT were found, of whom 20 had NF. Hydrocephalus was found in 4 children with NF (20%) and in 5 without NF (33.3%). In 6 of the children, ventricular dilatation with signs of acute increased intracranial pressure already existed at the time of diagnosis and the hydrocephalus was shunted at this time. In the other 3 children, all with NF, the hydrocephalus resulted from slowly developing aqueductal stenosis, leading in 2 to severe visual acuity deterioration. The results suggest that in children with VPT and NF, hydrocephalus, and especially hydrocephalus resulting from aqueductal stenosis, is more frequent than in the general population of NF patients, and less frequent than in VPT patients without NF. The possibility of the indolent development of hydrocephalus should be borne in mind while following children with NF. The optic nerve, when already involved with a glioma, is more vulnerable to increased pressure. Thus, in children with VPT and NF, any ventricular dilatation should lead to a consideration of early shunting.

Methotrexate treatment protocols and the central nervous system: significant cure with significant neurotoxicity

Methotrexate can influence the central nervous system through several metabolic toxic pathways. These effects can be categorized as immediate, acute to subacute, or chronic neurologic syndromes. The acute to subacute syndrome occurs frequently in acute lymphoblastic leukemia treatment protocols, generally manifesting with focal neurologic signs and changes seen on magnetic resonance imaging and single photon emission computed tomography. While in some patients the neurotoxicity is transient and benign and allows for continuation of chemotherapy, in others it can be quite severe and debilitating, leading to permanent neurologic deficits. The need to modify the treatment protocols when neurotoxicity appears is not fully established. It is also unknown whether the use of sufficient amounts of leucovorin can overcome the toxic effects of the drug.

Apparently unrelated clones shown by spectral karyotyping to represent clonal evolution of cryptic t(10;11)(p13;q23) in a patient with acute monoblastic leukemia

The accurate genetic classification of acute leukemia is of the utmost clinical importance for treatment stratification. In the present study, we report on a young girl with aggressive acute monoblastic leukemia (AML) (M5b) with skin, lymph node, and bone marrow involvement, in whom cytogenetic analysis revealed three clones with different secondary chromosomal changes. Two clones had the secondary +8 and del(9q) aberrations, with the der(11)t(1;11) in the second one; the third clone was apparently unrelated to the others, and had add(7)(p?21),-13,+22. Using the spectral karyotyping (SKY) technique, we found that all three clones originated from a common clone that harbored the hidden primary t(10;11)(p13;q23) or its derivatives, suggesting clonal evolution. The first clone had the balanced t(10;11), the second had its derivative, der(10)t(10;11), and the third had the other derivative, der(11)t(10;11). On fluorescence in situ hybridization (FISH), MLL gene splitting, with translocation of its centromeric portion to 10p, and deletion of its telomeric portion, was demonstrated. In conclusion, the detection of the very poor prognostic t(10;11) aberration in AML, was possible by complementing the traditional cytogenetic analysis with SKY and FISH.

Improved outcome in childhood B-cell lymphoma with the intensified French LMB protocol

BACKGROUND

During the last 20 years, 120 children with B cell lymphoma were treated at the National Pediatric Hematology/Oncology Center of Israel. Until 1986, 63 patients received an institutional protocol (BMC), and thereafter 57 patients received a modified French LMB protocol. We report the results of a retrospective analysis comparing the results of these two protocols.

PROCEDURE

Patient characteristics were similar in both groups except for stage of disease and lactate dehydrogenase (LDH) levels. Significantly more patients in the LMB group had higher stage disease, and the LDH levels also were higher (<600 microg/ml).

RESULTS

Fifty-four of fifty-seven children on the modified LMB protocol are alive, disease-free, with an overall event-free survival of 94% (median follow-up of 73 months). Event-free survival for stages I, II, and III patients is 100%, and for stage IV 77%, whereas the overall event-free survival was 58% among 63 children treated previously, and for stage IV patients only 10%. Severe marrow suppression and neutropenic enterocolitis were the major complications of this intensive protocol.

CONCLUSIONS

Intensive chemotherapy with a modified LMB protocol and modern supportive care result in a high cure rate of childhood B cell lymphoma even in patients with advanced disease.

Subacute central nervous system degeneration in a child: an unusual manifestation of ifosfamide intoxication

A 5-year-old child with desmoplastic small round-cell tumor was treated with a protocol of very-high-dose, short-term chemotherapy, containing HD-CAV (cyclophosphamide, doxorubicin, vincristine, and mesna), ifosfamide, and etoposide. Two days after the initiation of ifosfamide, he exhibited new-onset lethal encephalopathy manifested by subacutely progressive cerebellar and then temporal and frontocortical degeneration leading to a vegetative state and eventually to death. A full work-up, including brain biopsy, was negative, excluding infections and metabolic or vascular causes. Ifosfamide is known to be capable of causing acute encephalopathy that can be severe but is generally reversible. This child showed a very atypical progressive, lethal course of ifosfamide toxicity. The possibility of this complication should be considered when high-dose ifosfamide treatment is planned for children.

Gaucher disease: the origins of the Ashkenazi Jewish N370S and 84GG acid beta-glucosidase mutations

Type 1 Gaucher disease (GD), a non-neuronopathic lysosomal storage disorder, results from the deficient activity of acid beta-glucosidase (GBA). Type 1 disease is panethnic but is more prevalent in individuals of Ashkenazi Jewish (AJ) descent. Of the causative GBA mutations, N370S is particularly frequent in the AJ population, (q approximately .03), whereas the 84GG insertion (q approximately .003) occurs exclusively in the Ashkenazim. To investigate the genetic history of these mutations in the AJ population, short tandem repeat (STR) markers were used to map a 9.3-cM region containing the GBA locus and to genotype 261 AJ N370S chromosomes, 60 European non-Jewish N370S chromosomes, and 62 AJ 84GG chromosomes. A highly conserved haplotype at four markers flanking GBA (PKLR, D1S1595, D1S2721, and D1S2777) was observed on both the AJ chromosomes and the non-Jewish N370S chromosomes, suggesting the occurrence of a founder common to both populations. Of note, the presence of different divergent haplotypes suggested the occurrence of de novo, recurrent N370S mutations. In contrast, a different conserved haplotype at these markers was identified on the 84GG chromosomes, which was unique to the AJ population. On the basis of the linkage disequilibrium (LD) delta values, the non-Jewish European N370S chromosomes had greater haplotype diversity and less LD at the markers flanking the conserved haplotype than did the AJ N370S chromosomes. This finding is consistent with the presence of the N370S mutation in the non-Jewish European population prior to the founding of the AJ population. Coalescence analyses for the N370S and 84GG mutations estimated similar coalescence times, of 48 and 55.5 generations ago, respectively. The results of these studies are consistent with a significant bottleneck occurring in the AJ population during the first millennium, when the population became established in Europe.

Analysis and classification of 304 mutant alleles in patients with type 1 and type 3 Gaucher disease

Gaucher disease results from the inherited deficiency of the enzyme glucocerebrosidase (EC 3.2.1.45). Although >100 mutations in the gene for human glucocerebrosidase have been described, most genotype-phenotype studies have focused upon screening for a few common mutations. In this study, we used several approaches-including direct sequencing, Southern blotting, long-template PCR, restriction digestions, and the amplification refraction mutation system (ARMS)-to genotype 128 patients with type 1 Gaucher disease (64 of Ashkenazi Jewish ancestry and 64 of non-Jewish extraction) and 24 patients with type 3 Gaucher disease. More than 97% of the mutant alleles were identified. Fourteen novel mutations (A90T, N117D, T134I, Y135X, R170C, W184R, A190T, Y304X, A341T, D399Y, c.153-154insTACAGC, c.203-204insC, c.222-224delTAC, and c.1122-1123insTG) and many rare mutations were detected. Recombinant alleles were found in 19% of the patients. Although 93% of the mutant alleles in our Ashkenazi Jewish type 1 patients were N370S, c.84-85insG, IVS2+1G-->A or L444P, these four mutations accounted for only 49% of mutant alleles in the non-Jewish type 1 patients. Genotype-phenotype correlations were attempted. Homozygosity or heterozygosity for N370S resulted in type 1 Gaucher disease, whereas homozygosity for L444P was associated with type 3. Genotype L444P/recombinant allele resulted in type 2 Gaucher disease, and homozygosity for a recombinant allele was associated with perinatal lethal disease. The phenotypic consequences of other mutations, particularly R463C, were more inconsistent. Our results demonstrate a high rate of mutation detection, a large number of novel and rare mutations, and an accurate assessment of the prevalence of recombinant alleles. Although some genotype-phenotype correlations do exist, other genetic and environmental factors must also contribute to the phenotypes encountered, and we caution against relying solely upon genotype for prognostic or therapeutic judgements.

Tc-99m MIBI to evaluate children with Ewing's sarcoma

PURPOSE

Tc-99m MIBI has been used increasingly to evaluate benign and malignant tumors because of its tumor-seeking properties and ability to provide an imaging assessment of multiple-drug resistance. This study investigated the clinical utility of Tc-99m MIBI in the management of Ewing's sarcoma in children.

METHODS

Thirteen Tc-99m MIBI studies in nine (six male, three female) patients ages 6.5 to 20 years (mean, 13.4 years) with Ewing's sarcoma were reviewed. All patients had imaging studies at diagnosis, and four had follow-up studies during or after therapy. Scintigraphy was evaluated for Tc-99m MIBI uptake within the tumor and in metastases, which other imaging modalities had shown to be present in four patients. Scintigraphic results were correlated with the clinical course in all patients and with tumor P-glycoprotein status in six patients.

RESULTS

Tc-99m MIBI accumulated in 6 of 9 primary tumors and did not accumulate in one recurrent tumor. No metastases showed Tc-99m MIBI uptake. The presence or absence of Tc-99m MIBI uptake at diagnosis or after therapy carried no prognostic significance. Tc-99m MIBI was present in the two tumors that were P-glycoprotein positive and in only one of four tumors that were P-glycoprotein negative.

CONCLUSION

Tc-99m MIBI imaging does not appear to be useful in Ewing's sarcoma.

Increased operative bleeding during orthopaedic surgery in patients with type I Gaucher disease and bone involvement

To aid clinicians in identifying patients with type I Gaucher disease who are at risk of excessive bleeding, we reviewed the coagulation parameters of six affected patients with bone involvement who underwent orthopaedic surgery at two centers, and of 22 patients under treatment at another, seven of whom had total splenectomy. All patients were of Jewish Ashkenazi origin. Among the latter group, prolonged prothrombin time was noted in 81%. Incidence of clotting factor deficiency were as follows: factor XI, 36.3%; V, 31.8%; VIII, 27.2%; IX, 13.6%; and XII, 27.2%. Most of the abnormalities occurred in the non-splenectomized patients. Two of the six orthopaedic surgery patients had excessive intraoperative and postoperative bleeding. One, who underwent spinal decompression had prolonged prothrombin time, and the other, who had total hip replacement, showed a deficiency of factor XI. The second patient's hemoglobin level was maintained with transfusion of fresh frozen plasma during contralateral hip arthroplasty five months later. We suggest that preoperative evaluation of clotting factors and replacement therapy may prevent excessive bleeding in patients with type I Gaucher disease.

Delayed growth and puberty in patients with Gaucher disease type 1: natural history and effect of splenectomy and/or enzyme replacement therapy

BACKGROUND

Growth retardation in childhood was only recently recognized as a prominent feature of Gaucher disease type 1, but there are few data on both the pubertal development and the final outcome of growth and sexual maturation.

OBJECTIVE

To investigate the natural pattern of growth and puberty in patients with Gaucher disease type 1 and the effect of splenectomy and enzyme replacement therapy.

METHODS

We retrospectively analyzed growth and puberty in 57 patients with Gaucher disease type 1; 52 were followed since childhood and/or prepuberty and 42 have reached sexual maturity and final height. In the analysis we considered severity of disease, time of splenectomy, and start of enzyme replacement therapy.

RESULTS

Deceleration of growth at age 3-5 years was observed in 30 of 57 patients followed since early childhood while untreated: height-SDS decreased from -0.34 +/- 0.42 at age 0-3 years to -1.93 +/- 0.95 (P < 0.01) at age 7-10 years and was more pronounced with severe disease. A high prevalence (59.6%) of delayed puberty, which was more frequent with severe disease, was observed in 47 patients followed before and throughout puberty. No primary endocrine pathology was found. All patients, untreated as well as treated, with growth and pubertal delay had a spontaneous catch-up, achieved full sexual maturation, and most (83.3%) reached a final height within the range of parental height-standard deviation score. Splenectomy (partial and/or total) performed in 20 patients while still growing had a beneficial effect on growth, which was temporary in some and did not affect puberty. ERT improved growth in 11 patients who started therapy before puberty, as evidenced by a progressive increase in the height-SDS, and seemed to normalize the onset of puberty.

CONCLUSIONS

Growth retardation in childhood and delay of puberty are characteristic of Gaucher disease type 1 and are more frequent with severe disease. There is a spontaneous catch-up later in life and most patients reach a final height within their genetic growth potential. Enzyme replacement therapy apparently normalizes growth and possibly also the onset of puberty.

Visual pathway tumor: a heterogeneous tumor with a variable clinical course

The aim of the study was to delineate the clinical characteristics of visual pathway tumor in children without neurofibromatosis-I. The authors reviewed the charts of all patients meeting these criteria (n = 12) who were followed in their center over a 13-year period. In 8 patients the disease was relentlessly progressive, and imaging showed a chiasmatic/hypothalamic, exophytic globular lesion. The remainder had a benign course with long periods of tumor stability; one showed some spontaneous visual improvement. The lesions of the latter subgroup were multilobular, with elongated posterior extension into the optic tract. This differentiation, according to the imaging findings, may have significant therapeutic implications. In the first type, every effort should be made to arrest the disease and decrease the size of the lesion, whereas in the second, despite decreased visual ability, careful observation in the appropriate approach. There are as yet no known biological markers to better delineate these two types of tumor behavior.

Prognostic factors in non-metastatic limb osteosarcoma: A 20-year experience of one center

The purpose of this study was to evaluate the prognostic significance of variables in osteosarcoma. We performed a retrospective analysis of 35 patients with non-metastatic limb osteosarcoma that were treated between 1973 and 1994. The following variables were evaluated: age, sex, ethnic group, tumor histology and primary site, alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels at diagnosis, treatment regimen, and the histologic response to treatment. Three variables showed significant correlation with prognosis: i) histologic response to preoperative treatment. Disease-free survival (DFS) was 89% in patients with grade III-IV histologic response after a median follow-up (MFU) of 64 months, 67% in patients with grade II after an MFU of 64 months, the patients with grade I response died within 15 months (p<0.0001); ii) treatment regimen. DFS was 83% after an MFU of 42 months, 62% after an MFU of 82 months, and 30% after an MFU of 177 months in patients treated by the 90's, 80's, and 70's protocols, respectively (p<0.05); iii) corrected ALP (cALP) levels at diagnosis. DFS was 78% after an MFU of 88 months in patients with cALP levels <200, and 32% after an MFU of 56 months in patients with cALP levels >200 (p=0.01). Low ALP levels, good histologic response to preoperative chemotherapy, and the new therapeutic regimen correlated with good prognosis in patients with osteosarcoma.

Anaphylactoid reaction to imiglucerase, but not to alglucerase, in a type I Gaucher patient

Imiglucerase, the recombinantly produced enzyme, is gradually replacing the human placental derived alglucerase in the treatment of gaucher patients. We describe the first case, to the best of our knowledge, of an anaphylactoid reaction to imiglucerase in a patient who tolerated alglucerase. The patient was diagnosed at the age of 2 4/12 years with anemia and hepatosplenomegaly. Over the years he had suffered from marked splenomegaly, thrombocytopenia and recurrent bleeding episodes. At the age of 24 he started treatment with imiglucerase. After 3 months of treatment, immediately after starting an infusion, he experienced flushing, cough, tachycardia, palpitation, chest pain and excessive sweating, which reoccurred on a consecutive administration. Substitution with alglucerase was tolerated well, with only mild rash when he was premedicated with benadryl. Immediate skin tests to alglucerase, imiglucerase and gelatin were negative. IgG against alglucerase was undetectable. The in vitro mast cell degranulation test was positive for alglucerase, imiglucerase heamaccel (a gelatin based plasma substitute, which is a component of imiglucerase). This sensitivity to imiglucerase but not to alglucerase, raises the question of future treatment for this patient, since the production of alglucerase may cease, once imiglucerase production will cover the need for replacement enzyme.

Involvement of the foot and ankle in patients with Gaucher disease

Of 48 children with type I Gaucher disease treated at our hospital, 11 had involvement of the foot and ankle that first appeared in adolescence. Follow-up ranged from 3 to 27 years (average, 10 years). We reviewed their clinical and radiographic histories. Patients presented with four types of pain: six (7 events of pain) complained of dull pain defined as nonspecific; seven (11 events) had severe pain caused by bone crisis; two (2 events) had moderate progressive pain caused by pathological fractures; and one had painful swollen ankles caused by degenerative arthritis. Greater awareness of these complications in patients with Gaucher disease will prevent misdiagnosis and lead to early treatment.

Metastatic brain involvement in Ewing family of tumors in children

OBJECTIVE

To evaluate the incidence and clinical characteristics of CNS involvement in Ewing family of tumors (EF) in children.

METHODS

Chart reviews of children with EF treated in our center from 1972 to 1997. Clinical and imaging data regarding possible CNS involvement were collected.

RESULTS

During this 25-year period, 80 children with EF were treated. Intracranial involvement was found in eight (10%) children: the brain was involved in seven children (8.8%) and a retro-orbital metastasis without parenchymal brain involvement was noted in one child. Metastases were localized intrahemispherically, or in the cerebellum or the basal ganglia. Intracranial spread was hematogenous in five children and by contiguous spread from the skull in three children. Intracranial involvement was diagnosed 1.3 to 11 years from initial presentation. Seizures and hemiparesis were the main neurologic complications.

CONCLUSIONS

The rate of parenchymal brain involvement in our patients with EF was 8.8%. Spread was mainly hematogenous. Substantial morbidity was associated with CNS disease, which appeared in most patients late in the course of disease.

Mutations of the adenomatous polyposis coli and p53 genes in a child with Turcot's syndrome

Turcot's syndrome is a rare heritable complex that is characterized by an association between a primary neuroepithelial tumor of the central nervous system and multiple colonic polyps. The aim of this study was to analyze genetic alterations in a case of Turcot's syndrome in a 10.5-year-old boy in whom a colorectal tumor developed 3.5 years following astrocytoma. An APC germline non-sense mutation at codon 1284 leading to a truncated protein was identified, as was a somatic p53 mutation in the colorectal carcinoma in exon 7, codon 244. The latter was not identified in the primary astrocytoma. However, immunohistochemistry revealed high p53 protein expression in both tumors, suggesting an additional p53 mutation in the primary astrocytic tumor. The diverse p53 mutations observed in this unique syndrome in two different sites and stages of the disease may shed light on the multistep progression of the malignant events.

Diffuse brain stem gliomas. Are we improving outcome?

We reviewed our experience with diffuse brain stem glioma (dBSG) to evaluate whether any improvement of outcome had occurred in our patients over the years. Of the 24 children referred to our department with suspected dBSG from 1981 to 1997, 5 had a different final diagnosis based on the clinical course. Mean survival in the remainder was 16+/-9.8 months from diagnosis. Survival increased with a longer interval from onset of symptoms to diagnosis (12.9+/-9.0 months with an interval of 1-4 weeks; 19.50+/-10.8 months with a longer interval). Visual symptoms at presentation were associated with a poorer prognosis. Survival was better in the 3- to 5-year age group (at diagnosis). Overall, a trend toward a slight improvement in survival was seen over the years, which we presumptively attribute to the introduction of intensive chemotherapy for these patients. We suggest that chemotherapy may be important in the management of dBSG until a better modality is found.

Low-dose high-frequency enzyme replacement therapy prevents fractures without complete suppression of painful bone crises in patients with severe juvenile onset type I Gaucher disease

Patients with type I Gaucher disease often present as adults with a mild disease and with less severe genetic mutations, especially 1226G/1226G (N370S/N370S). Patients presenting as children have an excess of compound heterozygotes of N370S and other mutations, such as 84GG, 1448C (L444P) and IVS2 + 1 in whom bone disease is common. We report our experience with low-dose high-frequency enzyme replacement therapy in such severely affected children. Ten patients (with severe juvenile onset type I Gaucher disease) were treated. Alglucerase (Ceredase) was infused at 30 units/kg/month in 13 fractions/month for more than one year. Bone disease was used as the main criterion for evaluating treatment results. No fractures occurred in spite of the fact that bone crises occurred in four patients after 12 to 24 months of treatment, in two during the third year, and in one during the fifth year. Nonosseous manifestations improved with treatment. The ability of low-dose high frequency alglucerase to prevent fractures in the presence of continuing bone crises was demonstrated.

Splenic "regeneration" after partial splenectomy for Gaucher disease: histological features

Partial splenectomy for Gaucher disease is often followed by reenlargement of the splenic remnant. It remains unclear if this process is due to tissue regeneration or to continued deposition of glucocerebroside in the reticuloendothelial system or both. We compared the splenic architecture before and after reenlargement in three cases of failed repeated partial splenectomy after two, six and five years. Using the number of lymphoid follicles per hundred low power fields (LF/LPF) as an arbitrary index, we found that prior to the first operation 18, 20 and 27 lymphoid follicles were present per one hundred low power fields, while at the second operation, the corresponding rates were 11, 15 and 17; in control spleens, an average of 712.5 lymphoid follicles were present in one hundred low power fields. The difference in the LF/LPF ratio before and after reenlargement, led us to speculate that splenic re-enlargement in Gaucher disease is mainly the result of the continued deposition of the glucocerebroside in the reticuloendothelial system of the splenic remnant, though some degree of true regeneration as well cannot be completely ruled out. These findings are compared with animal studies and results for partial splenectomy on humans, performed for trauma. Further studies in patients with Gaucher disease are warranted to better define the underlying mechanism of splenic reenlargement.

Linkage disequilibrium of common Gaucher disease mutations with a polymorphic site in the pyruvate kinase (PKLR) gene

Gaucher disease (GD), caused by a deficiency of the lysosomal enzyme glucocerebrosidase (GBA), is the most common human glycolipid storage disease. The incidence of the disease is particularly high in the Ashkenazi Jewish population, with a carrier frequency of 0.068. The 1226A-->G and 84GG mutations are the two predominant disease-causing alleles. We investigated the association of various mutations in the GBA gene with different alleles of a highly polymorphic site in the adjacent pyruvate kinase (PKLR) gene. Ninety-seven unrelated type I GD patients of various genotypes were studied to determine their genotype for the PKLR gene trinucleotide repeat polymorphism. One hundred out of 104 (96%) alleles carrying the 1226G mutation also carried the A1 allele of the PKLR gene, which is present in only 6.7% of the control population. The calculated linkage disequilibrium between 1226G and the A1 allele of the PKLR gene is 0.957. Mutation 84GG was found to be uniquely associated with the PKLR A6 allele, with a linkage disequilibrium of 1.00. The association of several less frequent GD mutations with PKLR alleles was also studied. These results support the hypothesis that the 1226G and 84GG mutations in the Ashkenazi Jewish population each originated in a single founder. Further studies of the association of the 1226G and 84GG mutations with PKLR alleles in European non-Jewish GD patients could help in the study of the chronological order of these mutations and may shed light on the history of the Ashkenazi Jews in the past two millennia.