Duplication of 7q34 is specific to juvenile pilocytic astrocytomas and a hallmark of cerebellar and optic pathway tumours

Background:

Juvenile pilocytic astrocytomas (JPA), a subgroup of low-grade astrocytomas (LGA), are common, heterogeneous and poorly understood subset of brain tumours in children. Chromosomal 7q34 duplication leading to fusion genes formed between KIAA1549 and BRAF and subsequent constitutive activation of BRAF was recently identified in a proportion of LGA, and may be involved in their pathogenesis. Our aim was to investigate additional chromosomal unbalances in LGA and whether incidence of 7q34 duplication is associated with tumour type or location.

Methods and results:

Using Illumina-Human-Hap300-Duo and 610-Quad high-resolution-SNP-based arrays and quantitative PCR on genes of interest, we investigated 84 paediatric LGA. We demonstrate that 7q34 duplication is specific to sporadic JPA (35 of 53 – 66%) and does not occur in other LGA subtypes (0 of 27) or NF1-associated-JPA (0 of 4). We also establish that it is site specific as it occurs in the majority of cerebellar JPA (24 of 30 – 80%) followed by brainstem, hypothalamic/optic pathway JPA (10 of 16 – 62.5%) and is rare in hemispheric JPA (1 of 7 – 14%). The MAP-kinase pathway, assessed through ERK phosphorylation, was active in all tumours regardless of 7q34 duplication. Gain of function studies performed on hTERT-immortalised astrocytes show that overexpression of wild-type BRAF does not increase cell proliferation or baseline MAPK signalling even if it sensitises cells to EGFR stimulation.

Conclusions and interpretation:

Our results suggest that variants of JPA might arise from a unique site-restricted progenitor cell where 7q34 duplication, a hallmark of this tumour-type in association to MAPK-kinase pathway activation, potentially plays a site-specific role in their pathogenesis. Importantly, gain of function abnormalities in components of MAP-Kinase signalling are potentially present in all JPA making this tumour amenable to therapeutic targeting of this pathway.

Telomere maintenance and dysfunction predict recurrence in paediatric ependymoma

We have recently described the enzymatic subunit of telomerase (hTERT) as an important prognostic marker for paediatric ependymoma. Because of the lack of good, representative pre-clinical models for ependymoma, we took advantage of our large cohort of ependymoma patients, some with multiple recurrences, to investigate telomere biology in these tumours. Our cohort consisted of 133 ependymomas from 83 paediatric patients and included 31 patients with recurrences. Clinical outcome was measured as overall survival, progression-free survival and response to therapy. In all 133 tumours, hTERT expression correlated with proliferative markers, including MIB-1 index (P<0.0001) and mitotic index (P=0.005), as well as overall tumour grade (P=0.001), but not with other markers of anaplasia. There was no correlation between telomere length and hTERT expression or survival. Surprisingly, prior radiation or chemotherapy neither induced sustained DNA damage nor affected telomere maintenance in recurrent tumours. There was an inverse correlation between hTERT expression and telomere dysfunction as measured by gamma H2AX expression (P=0.016). Combining gamma H2AX and hTERT expressions could segregate tumours into three different survival groups (log rank, P<0.0001) such that those patients whose tumours expressed hTERT and showed no evidence of DNA damage had the worst outcome. This study emphasises the importance of telomere biology as a prognostic tool and telomerase inhibition as a therapeutic target for paediatric ependymoma. Furthermore, we have demonstrated that analysing tumours as they progress in vivo is a viable approach to studying tumour biology in humans.

CONTRIBUTION OF DNA COPY-NUMBER VARIATION (CNV) TO CANCER SUSCEPTIBILITY AND LARGE-SCALE GENOME ALTERATIONS IN OSTEOSARCOMA (OS)

Introduction: OS, a common Li-Fraumeni syndrome (LFS)-associated neoplasm, is a common bone malignancy of children and adolescents. Sporadic OS is also characterized by young age of onset and high genomic instability, suggesting a genetic contribution to disease. This study examined the contribution of novel DNA structural variation elements, CNVs, to OS susceptibility. Given our finding of excessive constitutional DNA CNV in LFS patients, which often coincide with cancer-related genes, we hypothesized that constitutional CNV may also provide clues about the aetiology of LFS-related sporadic neoplasms like OS. Methods: CNV in blood DNA of 26 patients with sporadic OS was compared to that of 263 normal control samples from the International HapMap project, as well as 62 local controls. Analysis was performed on DNA hybridized to Affymetrix genome-wide human SNP array 6.0 by Partek Genomic Suite. Results: There was no detectable difference in average number of CNVs, CNV length, and total structural variation (product of average CNV number and length) between individuals with OS and controls. While this data is preliminary (small sample size), it argues against the presence of constitutional genomic instability in individuals with sporadic OS. Conclusion: We found that the majority of tumours from patients with sporadic OS show CN loss at chr3q13.31, raising the possibility that chr3q13.31 may represent a “driver” region in OS aetiology. In at least one OS tumour, which displays CN loss at chr3q13.31, we demonstrate decreased expression of a known tumour suppressor gene located at chr3q13.31. We are investigating the role ofchr3q13.31 in development of OS.

Risk stratification in cancer predisposition syndromes: lessons learned from novel molecular developments in Li-Fraumeni syndrome

Germ-line mutations in specific genes predispose family members to cancer. Prediction of the exact tumor type and timing of cancer initiation is fundamental to the development of management strategies for these individuals. Recent advances in our understanding of the general processes that control cancer initiation may enable us to tailor more precise risk stratification. This, in turn, will lead to more effective early detection strategies, which would result in more favorable clinical outcomes. In this review, we highlight the steps and methods used to reach this futuristic model.

Toxicity and outcome of children with treatment related acute myeloid leukemia

BACKGROUND

The aim of this study was to evaluate the clinical course and outcome of children with treatment related acute myeloid leukemia (tAML) and compare them to children with primary AML (pAML).

PROCEDURE

We retrospectively reviewed the demographic, treatment, toxicity, and outcome data of children with tAML and treatment related myelodysplastic syndrome (tMDS), treated at our institution between 1975 and 2005. We compared these parameters with matched controlled children with pAML. Finally we compared overall survival (OS) for tAML with all pAML children treated at the study era in our institution.

RESULTS

Twenty-one patients with tAML (n = 19) and tMDS (n = 2) were identified. Three years event-free survival (EFS) and OS were both 14 +/- 8%. Compared to pAML patients, tAML had a higher rate of adverse cytogenetics (P < 0.008) and inferior OS (P = 0.027) but no significant difference in treatment toxicity or death. All survivors were treated with allogeneic hematopoietic stem cell transplantation (HSCT).

CONCLUSIONS

In this population based report of pediatric tAML, outcome was poor and was related to a higher probability of poor cytogenetic features rather than excessive toxicities or inability to deliver therapy. HSCT should be considered for patients with tAML. These preliminary findings should set the stage for prospective cooperative studies.

Telomere biology of pediatric cancer

One of the hallmarks of cancer is limitless proliferative capacity, which is tightly associated with the ability to maintain telomeres. Over the last decade, the telomere biology of pediatric cancers has begun to be elucidated. Most pediatric leukemias and embryonal solid tumors activate the enzyme telomerase, a specialized reverse transcriptase that adds nucleotide repeats to telomeres. In general, high levels of tumor telomerase expression are associated with unfavorable outcome, although results vary according to tumor type. Some pediatric tumors, including osteosarcoma and glioblastoma multiforme, lack telomerase activity and maintain telomeres via a recombination-based mechanism called ALT (alternative lengthening of telomeres). Telomerase is a highly attractive therapeutic target for pediatric cancer because the enzyme plays a key role in conferring cellular immortality, is present in most tumors, and is relatively specific for cancer cells. Telomerase inhibitors have been evaluated in preclinical models of adult cancers, but few studies have been conducted on pediatric cancers. Further research is required to define how telomere biology can be used to clinical advantage in malignancies of childhood.

Younger age of cancer initiation is associated with shorter telomere length in Li-Fraumeni syndrome

Li-Fraumeni syndrome (LFS) is a cancer predisposition syndrome frequently associated with germ line TP53 mutations. Unpredictable and disparate age of cancer onset is a major challenge in the management of LFS. Genetic modifiers, including the MDM2-SNP309 polymorphism, and genetic anticipation have been suggested as plausible explanations for young age of tumor onset, but the molecular mechanisms for these observations are unknown. We speculated that telomere attrition will increase genomic instability and cause earlier tumor onset in successive generations. We analyzed mean telomere length and MDM2-SNP309 polymorphism status in individuals from multiple LFS families and controls. A total of 45 peripheral blood lymphocyte samples were analyzed from 9 LFS families and 15 controls. High rate of MDM2-SNP309 was found in TP53 carriers (P = 0.0003). In children, telomere length was shorter in carriers affected with cancer than in nonaffected carriers and wild-type controls (P < 0.0001). The same pattern was seen in adults (P = 0.002). Within each family, telomere length was shorter in children with cancer than in their nonaffected siblings and their noncarrier parents. Telomere attrition between children and adults was faster in carriers than in controls. Our results support the role of MDM2-SNP309 as a genetic modifier in LFS. The novel finding of accelerated telomere attrition in LFS suggests that telomere length could explain earlier age of onset in successive generations of the same family with identical TP53/MDM2-SNP309 genotypes. Furthermore, telomere shortening could predict genetic anticipation observed in LFS and may serve as the first rational biological marker for clinical monitoring of these patients.

Low prevalence of complications in severe neutropenic children with cancer in the unprotected environment of an overnight camp

BACKGROUND

The high risk of infection and other complications in severely neutropenic pediatric oncology patients receiving chemotherapy has led to development of a variety of preventive measures including isolation and diet restrictions. In order to examine the potential impact of these measures, we evaluated the outcomes of such patients attending a recreational summer camp.

METHODS

We collected data on all children who attended an overnight summer camp for children with cancer during the years 1999-2004, and who were either severely neutropenic or at a high-intensity phase of chemotherapy. Outcome measures included fever, bleeding, hospitalization, and clinical or laboratory evidence of infection. The observation period included both, the 2-week camp experience and 30 days post-camp.

RESULTS

The study group was comprised of 34 patients. Although nine (24%) were hospitalized for management of fever and neutropenia, only one patient had clinical or culture-positive evidence of an invasive infectious agent. No bleeding episode was recorded and most patients attended all camp activities.

CONCLUSIONS

Our results support the safety and feasibility of severely neutropenic patients with cancer to attend the non-isolated, non-sterile environment of a summer camp. These findings may be applicable to school and other social settings.

Outcome of secondary high-grade glioma in children previously treated for a malignant condition: A study of the Canadian Pediatric Brain Tumour Consortium

BACKGROUND AND PURPOSE

Reports of secondary high-grade glioma (HGG) in survivors of childhood cancer are scarce. The aim of this study was to review the pattern of diagnosis, the treatment, and outcome of secondary pediatric HGG.

PATIENTS AND METHODS

We performed a multi-center retrospective study among the 17 paediatric institutions participating in the Canadian Pediatric Brain Tumour Consortium (CPBTC).

RESULTS

We report on 18 patients (14 males, 4 females) treated in childhood for a primary cancer, who subsequently developed a HGG as a second malignancy. All patients had previously received radiation therapy +/- chemotherapy for either acute lymphoblastic leukaemia (n=9) or solid tumour (n=9). All HGG occurred within the previous radiation fields. At the last follow-up, 17 patients have died and the median survival time is 9.75 months.

CONCLUSION

Although aggressive treatment seems to provide sustained remissions in some patients, the optimal management is still to be defined. Further documentation of such cases is necessary in order to better understand the pathogenesis, the natural history and the prevention of these tumours.

The role of telomere maintenance in the spontaneous growth arrest of pediatric low-grade gliomas

Spontaneous tumor regression of pediatric low-grade gliomas (PLGG). We speculated that lack of telomere maintenance is responsible for this behavior. We first looked for evidence of telomerase activity and alternative lengthening of telomeres (ALT) in 56 PLGG. Telomerase activity was observed in 0 of 11 PLGG, in contrast to 10 of 13 high-grade pediatric brain tumors. There was no ALT in 45 of 45 samples. We then applied Q-FISH to eight patients whose indolent PLGG underwent two metachronous biopsies over a lag of several years. Telomere shortening was observed in the second biopsy in all tumors, but not in normal brain control (P < .0001), indicating that lack of telomere maintenance is associated with continuous telomere erosion. Based on these observations, we found that younger PLGG patients, who exhibit more aggressive and frequently recurrent tumors, had significantly longer telomeres than older ones (P = .00014). Tumors with a terminal restriction fragment length <7.5 did not recur, whereas the presence of longer telomeres (>8.0) conferred a high likelihood of late recurrences in PLGG. Our findings provide a plausible biologic mechanism to explain the tendency of PLGG to exhibit growth arrest and spontaneous regression. Telomere maintenance may therefore represent the first known biologic prognostic marker in PLGG.

Telomere maintenance predicts progression and survival in pediatric intracranial ependymoma

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Background: Ependymoma is the third most common pediatric brain tumor. Despite the importance of surgical resection and pathology, its clinical course is highly unpredictable and the biological behavior is largely unknown. As part of ongoing studies to identify potential biological and therapeutic markers for the disease, we analyzed the role of telomere maintenance, which is required for cancers to sustain growth and evade senescence. Methods: We analyzed 111 primary and recurrent ependymomas that were resected at the Hospital for Sick Children in Toronto between 1986 and 2004. A tissue array was constructed. hTERT and γH2AX expression were evaluated. Thirty-one frozen samples were additionally analyzed for telomere length (TRF) and telomerase activity (TRAP assay). Results: Of the 111 samples, 40 tumors were hTERT(-) with progression-free survival (PFS) of 83±15% and 71 were hTERT(+) with PFS of 21±9% (p<0.0001). Of the 65 patients with primary ependymomas, five-yr overall survival (OS) were 84±7% and 41±7% for hTERT(-) and hTERT(+) tumors, respectively (p=0.001). There was good correlation between telomerase activity and hTERT expression (κ=0.637). Multivariate analysis revealed hTERT expression to be the single most important predictor of survival of all known pathological, clinical and treatment factors (HR 60.4 (CI 6.4–561)). TRF measurement revealed lack of alternative lengthening of telomeres (ALT) and heterogenous telomere length in pediatric ependymomas. We observed a trend for better prognosis with telomere dysfunction manifested by shorter telomeres and positive γH2AX. Conclusions: This study suggest that telomere maintenance represents the first known biologic prognostic factor for intracranial ependymomas. Telomerase activity highlights the importance of senescence in carcinogenesis and a possible target for novel treatment approaches for the disease.

No significant financial relationships to disclose.

Human Telomere Reverse Transcriptase Expression Predicts Progression and Survival in Pediatric Intracranial Ependymoma

Purpose

Pediatric intracranial ependymomas are a heterogeneous group of neoplasms with unpredictable clinical and biologic behavior. As part of ongoing studies to identify potential biologic and therapeutic markers, we analyzed the role of human telomere reverse transcriptase (hTERT; the catalytic subunit of telomerase) expression as a prognostic marker for this disease.

Patients and Methods

Primary intracranial ependymomas that were resected at our institution between 1986 and 2004 were identified through the pathology and oncology databases. A tissue array was constructed from the patient samples and hTERT expression was evaluated by immunohistochemistry. Twenty-one samples were also analyzed for telomerase activity (telomerase repeat amplification protocol assay).

Results

Eighty-seven tumors from 65 patients were analyzed. Five-year progression-free survival was 57% (SEM, 12%) and 21% (SEM, 8%) for hTERT-negative and hTERT-positive tumors, respectively (P = .002). Five-year overall survival was 84% (SEM, 7%) and 41% (SEM, 7%) for hTERT-negative and hTERT-positive tumors, respectively (P = .001). There was good correlation between telomerase activity and hTERT expression (κ = 0.637). Multivariate analysis revealed hTERT expression to be the single most important predictor of survival of all known pathologic, clinical, and treatment factors (hazard ratio, 60.4; 95% CI, 6.4 to 561). All four patients with hTERT-negative tumors at relapse are still alive, with median follow-up of 11.2 years.

Conclusion

In this study, hTERT expression was the strongest predictor of outcome and was independent of other clinical and pathologic prognostic markers. It represents a simple and reliable biologic prognostic factor for intracranial ependymomas. These results should be confirmed in larger prospective trials.

Epidermal growth factor receptor gene amplification and expression in disseminated pediatric low-grade gliomas

OBJECT

Pediatric low-grade gliomas (LGGs) are the largest group of central nervous system neoplasms in children. Although these tumors are generally benign, 5 to 10% of patients with pediatric LGGs present with leptomeningeal dissemination. The genetic and biological nature of these tumors is poorly understood. The authors looked for certain molecular abnormalities that may differentiate disseminated gliomas from the other pediatric LGGs.

METHODS

Comparative genomic hybridization (CGH) was applied to 18 pediatric LGGs. Six cases featuring disseminated pediatric LGGs were compared with 12 control cases involving nondisseminated pediatric LGGs. Fluorescence in situ hybridization (FISH) analysis and immunohistochemical analysis were used to highlight further specific genetic targets. The CGH revealed multiple chromosomal abnormalities in five of six cases with disseminated gliomas and in six of 12 control cases. No correlation was found between the number of chromosomal abnormalities and dissemination status. Amplification of chromosome 7 was noted in four of six cases with disseminated gliomas as opposed to one of 12 control cases (p = 0.02). The FISH analysis revealed epidermal growth factor receptor (EGFR) amplification in one case negative to chromosome 7 amplification by CGH, raising the amplification cases to five of six (p = 0.0038). Immunohistochemical analysis for EGFR was positive in six of six cases and in two of 12 control cases (p = 0.0015). At the end of a mean follow-up period of 7.2 years, all patients with disseminated gliomas are alive with variable but slow disease progression.

CONCLUSIONS

The high rate of EGFR gene amplification and protein expression in disseminated pediatric LGGs is intriguing and may have implications for our understanding of the role of EGFR in glioma genesis. Targeted therapies may be available for these children. Larger-scale studies are needed to establish further these findings.

Distinctive clinical course and pattern of relapse in adolescents with medulloblastoma

PURPOSE

To report the clinical course of adolescents with medulloblastoma, with specific emphasis on prognosis and pattern of relapse.

METHODS AND MATERIALS

We retrospectively studied the clinical course and outcomes of children aged 10-20 years with medulloblastoma, treated at centers throughout Canada between 1986 and 2003. To better assess time to relapse, a cohort of patients aged 3-20 years at diagnosis was generated.

RESULTS

A total of 72 adolescents were analyzed. Five-year overall survival and event-free survival rates were 78.3%+/-5.4% and 68.0%+/-6.2%, respectively. Late relapses occurred at a median of 3.0 years (range, 0.3-6.8 years). In univariate analysis, conventional risk stratification and the addition of chemotherapy to craniospinal radiation did not have prognostic significance. Female patients had improved overall survival (p=0.007). Time to relapse increased with age in a linear fashion. After relapse, patients faired poorly regardless of treatment modality. Patients who did not receive chemotherapy initially had improved progression-free survival at relapse (p=0.05).

CONCLUSIONS

Our study suggests that adolescents with medulloblastoma might have a unique prognosis and pattern of relapse, dissimilar to those in younger children. They might benefit from different risk stratifications and prolonged follow-up. These issues should be addressed in future prospective trials.

Weekly vinblastine in pediatric low-grade glioma patients with carboplatin allergic reaction

BACKGROUND

Carboplatin-based regimens have demonstrated activity in unresectable low-grade glioma (LGG) in children. Despite an interesting toxicity profile, the use of these regimens has been limited by the development of carboplatin hypersensitivity reaction (HSR) in up to 30% of patients. Desensitization has been the recommended approach for HSR. However, no guidelines have existed to aid physicians when carboplatin desensitization techniques fail.

METHODS

A pilot study of monotherapy with weekly vinblastine for LGG in 9 children who developed carboplatin HSR on a carboplatin and vincristine regimen was performed.

RESULTS

Vinblastine toxicity was moderate and readily manageable. None of the 9 patients had disease progression on therapy. Magnetic resonance imaging evaluation of tumor size from diagnosis to the end of vinblastine treatment showed 1 complete response (CR), 1 partial response (PR), 5 objective effects (OE), and 2 stable diseases (SD).

CONCLUSIONS

This experience suggested that weekly vinblastine has a good efficacy to toxicity ratio in the treatment of LGG and can be a valuable option for children who develop severe HSR.

Medulloblastoma in the second decade of life: a specific group with respect to toxicity and management: a Canadian Pediatric Brain Tumor Consortium Study

BACKGROUND

Most reported data of chemoradiotherapy protocols for the treatment of medulloblastoma describe children who were treated in the first decade of life. To consider the feasibility of this approach in adolescents, the authors studied their clinical course with specific emphasis on toxicity, tolerability, and prognosis.

METHODS

In this retrospective study, the authors examined the toxicity profiles and outcomes of children age 10-20 years with medulloblastoma who were treated at centers throughout Canada between 1986 and 2003. Detailed toxicity data from 2 chemotherapy protocols were collected for teenagers and were compared with data from a group of control patients age 5-10 years.

RESULTS

In total, 72 teenagers were analyzed. Grade >/= 2 ototoxicity and neurotoxicity occurred in 45% and 71% of chemotherapy-treated patients, respectively. Grade 3-4 hematotoxicty occurred in 95% of patients. Toxicity resulted in delay of treatment for 73% of patients and dose modification in 75% of patients, including protocol discontinuation in 25% of patients. Weight loss > 10% was encountered in 73% of patients and required intervention in 45% of patients. Teenagers had significantly more hematotoxicity and neurotoxicity compared with controls on both chemotherapeutic protocols. Ototoxicity was similar in both age groups. Toxicity resulted in significantly more treatment delays and dose modifications in teenager patients compared with controls. The 5-year overall and event-free survival rates (+/- standard deviation) were 78% +/- 6% and 70% +/- 6%, respectively. The mean time (+/- standard deviation) to disease recurrence was 3.2 +/- 2.2 years.

CONCLUSIONS

The increased toxicity rate and high incidence of treatment modifications in this study suggested that current pediatric protocols may require modifications for teenagers with medulloblastoma. The results highlighted several issues that should be addressed in future prospective trials.

Evolution of a T-B- SCID into an Omenn syndrome phenotype following parainfluenza 3 virus infection

Mutations in both of the recombination activating genes (RAG)1 and RAG2 can lead to either T-B-severe combined immune deficiency (SCID) or Omenn syndrome (OS), two diseases presenting with totally different clinical and laboratory manifestations. The fact that the same mutations can cause either T-B- SCID or OS, even within the same family, lends credibility to the hypothesis that an additional factor (autoantigen or exoantigen) is required in certain circumstances for the development of OS phenotype. We investigated three patients from the same extended family who presented as T-B- SCID due to a homozygous mutation (G1305T) in the RAG2 gene. Our data support the notion that mutated RAG proteins may not always be sufficient to cause OS phenotype, and show evolution from a T-B- SCID into a typical OS phenotype subsequent to parainfluenza 3 virus infection.

Risk of venous thromboembolism in pediatric patients with brain tumors

BACKGROUND

Venous thromboembolism (VTE) is a common event in adults with malignant brain tumors approaching 24% throughout the course of the disease. The high morbidity and mortality of this complication yielded several protocols for prevention of the disease in adults undergoing neurosurgery for brain tumors and possible primary prevention afterwards. We investigated the incidence and complications of VTE in pediatric neuro-oncology patients.

PROCEDURE

We analyzed, retrospectively, the files of all consecutive patients under the age of 18 years who were hospitalized for the treatment of brain tumors between the years 1990 and 2003 in two leading, closely related, Israeli neuro-oncology centers.

RESULTS

A total of 462 children were analyzed. Three hundred eighty-four patients underwent surgery and 78 were treated medically. Only three (0.64%) of the patients developed clinical episodes of VTE that were treated conservatively. Two of these patients developed intracranial bleeding while on secondary prevention for the disease.

CONCLUSIONS

Although this study has considerable limitations in terms of retrospective design, heterogeneous group of patients and diagnoses, the changing awareness for thrombosis over the last 14 years and the inclusion of symptomatic VTE events only, our surprising data suggest that, as opposed to adults, the risk of clinically significant VTE in children with brain tumors may be exceedingly low. These findings set the stage for future forthcoming evaluations in view of the prospective studies that were done in adults and the possible significant implications for the prevention and possible etiologies of the disease.

Multilineage hematopoietic engraftment after allogeneic peripheral blood stem cell transplantation without conditioning in SCID patients

Successful stem cell transplantation for patients with severe combined immunodeficiency (SCID) from matched family donors without conditioning results in engraftment of T lymphocytes. B lymphocytes engraft in only 50% of the cases, while myelopoiesis and erythropoiesis remain of host origin. Full hematopoietic engraftment was reported in one case after bone marrow transplantation without conditioning for a SCID patient. We studied three SCID patients who were transplanted with unmodified mobilized peripheral blood from HLA-identical family sex-mismatched members. They received megadoses of stem cells (18-23 x 10(6)CD34/kg). In contrast to the expected mixed chimerism that usually occurs in the absence of conditioning, we found in our patients 100% donor cell engraftment based on fluorescence in situ hybridization (FISH) and microsatellite techniques. Subset analysis of the engrafted cells using a multiparametric system enabling a combined analysis of morphology, immunophenotyping and FISH showed that both T and B lymphocytes and myeloid cells were of donor origin in two patients, while T lymphocytes and myeloid cells were of donor origin in the third. In the two cases with ABO incompatibility, erythroid engraftment was evidenced by blood group conversion from recipient to donor type. Multilineage donor engraftment is possible in SCID patients even without conditioning.

Detection of RAG mutations and prenatal diagnosis in families presenting with either T-B- severe combined immunodeficiency or Omenn's syndrome

It has been recently shown that mutations in both of the recombination activating genes RAG1 and RAG2 are involved in each of the two different types of severe combined immunodeficiency (SCID) syndromes: T-B- SCID and Omenn's syndrome (OS). The objective of the study was to search for novel mutations in the RAG genes and to offer prenatal diagnosis for families that have been identified as at risk of T-B- SCID or OS. Mutation analyses of polymerase chain reaction products of RAG1/RAG2 genes were performed in 14 cases (T-B- SCID = 6 and OS = 8). Consanguinity was reported in seven (50%) families. Four missense mutations in the RAG2 gene in six of eight OS patients and in four of six T-B- SCID patients were detected. The C1845T transition leading to a Tre215Ile substitution is a novel mutation. All but one of the patients were homozygous for the detected mutations, possibly reflecting the consanguinity in these families and the relative rarity of the disease-causing mutations. In addition, three putative polymorphic sites were found. Prenatal diagnosis was offered to seven families, but three of them declined genetic counseling for religious reasons. In the remaining families, four pregnancies were successfully completed, and in one case, the family chose to have an abortion because of a homozygous mutation. Mutations in RAG1/RAG2 genes were detected in only some of the T-B- SCID or OS patients, and the molecular basis for the remaining cases has yet to be elucidated. Important factors such as religious beliefs need to be considered when offering prenatal diagnosis to certain families.

Repeat computed tomographic scan within 24-48 hours of admission in children with moderate and severe head trauma

OBJECTIVE

To asses the yield and contribution of a routine predetermined repeat head computed tomographic (CT) scan within 24-36 hrs in pediatric patients with moderate to severe head trauma.

DESIGN

Records review.

SETTING

Five pediatric intensive care units.

PATIENTS

We reviewed the charts of 173 consecutive pediatric patients with moderate to severe head trauma (Glasgow Coma Scale score of < or = 11) that survived the first 24 hrs after being admitted to five Israeli trauma centers. Clinical data collected included status at admission, at the time between the first and second CT scans, and after the second scan. Head details of the first, second, and, if performed, third CT scan were collected. Treatment strategy during each period was recorded, including any change in treatment after each CT scan.

MEASUREMENTS AND MAIN RESULTS

A total of 47 (27%) of the second CT scans showed new lesions including six intracranial hemorrhages, 17 cases of worsening brain edema, and 18 newly diagnosed brain contusions. However, none of these findings necessitated surgical intervention or any change in therapy. Of the 67 patients who underwent a third CT scan, two cases required surgical intervention because of new findings in the third CT.

CONCLUSIONS

A second routine prescheduled head CT scan within 24-36 hrs after admission in pediatric patients with moderate to severe head trauma is unlikely to yield any change in therapy. Clinically and intracranial pressure-oriented CT scan may better select and diagnose patients who require changes in therapy, including surgery. Studies aimed to determine the ideal timing for the second are warranted.