G. Malcolm Taylor

HLA-A alleles and infectious mononucleosis suggest a critical role for cytotoxic T-cell response in EBV-related Hodgkin lymphoma

A proportion of classical Hodgkin lymphoma (HL) is believed to be causally related to infection with the ubiquitous lymphotropic EBV. The determining factors for development of EBV-related HL remain poorly understood, but likely involve immunological control of the viral infection. Accordingly, markers of the HLA class I region have been associated with risk of EBV-related HL. To study the host genetic component of EBV-related HL further, we investigated the lymphomas association with HLA-A*01 and HLA-A*02 simultaneously in the setting of infectious mononucleosis (IM), a risk factor for EBV-related HL, in a case-series analysis including 278 EBV-related and 656 EBV-unrelated cases of HL. By logistic regression, HLA-A*01 alleles [odds ratio (OR) per allele, 2.15; 95% CI, 1.60–2.88] were associated with increased and HLA-A*02 alleles (OR per allele, 0.70; 95% CI, 0.51–0.97) with decreased risk of EBV-related HL. These allele-specific associations corresponded to nearly 10-fold variation in risk of EBV-related HL between HLA-A*01 and HLA-A*02 homozygotes. History of IM was also associated with risk of EBV-related HL (OR, 3.40; 95% CI, 1.74–6.66). The association between history of IM and EBV-related HL was not seen in the presence of HLA-A*02 because this allele appeared to neutralize the effect of IM on EBV-related HL risk. Our findings suggest that HLA class I-restricted EBV-specific cytotoxic T-cell responses and events in the early immune response to EBV infection in IM play critical roles in the pathogenesis of EBV-related HL.

Incidence of childhood precursor B-cell acute lymphoblastic leukaemia in north-west England

A temporal increase in the incidence of childhood acute lymphoblastic leukaemia (ALL) in the UK has been noted. We present data from the Manchester Childrens Tumour Registry which provide strong evidence that the increase is a result of an increase in the precursor B-cell subtype. In the childhood peak (age 1-4 years), the annual increase in precursor B-cell ALL between 1980 and 1998 was 3.0% (p=0.024). Recent findings are consistent with the causal involvement of infections in precursor B-cell ALL.

The human leukocyte antigen class I region is associated with EBV-positive Hodgkin's lymphoma : HLA-A and HLA Complex Group 9 are putative candidate genes

Various studies have indicated that the human leukocyte antigen (HLA) region is associated with Hodgkins lymphoma. We recently showed a specific association of the HLA class I region with EBV-positive Hodgkins lymphoma cases. One haplotype of two consecutive microsatellite markers (D6S265 and D6S510) was overrepresented in the patient group, whereas another haplotype was underrepresented. Here, we did fine mapping of this region of ∼400 kb as a next step to find the causative single-nucleotide polymorphism(s) (SNP). To select candidate SNPs for screening the total study population, several known SNPs were determined by sequencing two individuals homozygous for either of the above-mentioned associated haplotypes. Seven SNPs displayed different alleles in these two individuals and were therefore analyzed in the total study population, including 238 Hodgkins lymphoma patients and 365 family-based controls. All seven SNPs showed significant association with the EBV-positive patient group. Two of these SNPs were analyzed in a Scottish Hodgkins lymphoma population and revealed significant associations as well. The associated SNPs are located nearby two putative candidate genes: HLA-A and HLA complex group 9. HLA-A represents the most interesting target because of its consistent expression in EBV-positive Hodgkins lymphoma cases and its ability to present EBV-derived peptides to cytotoxic T cells. (Cancer Epidemiol Biomarkers Prev 2006;15(11):2280–4)

A cross-linker-sensitive myeloid leukemia cell line from a 2-year-old boy with severe Fanconi anemia and biallelic FANCD1/BRCA2 mutations

Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital and developmental abnormalities, hypersensitivity to DNA cross‐linking agents such as mitomycin C (MMC), and strong predisposition to acute myeloid leukemia (AML). In this article, we describe clinical and molecular findings in a boy with a severe FA phenotype who developed AML by the age of 2. Although he lacked a strong family history of cancer, he was subsequently shown to carry biallelic mutations in the FANCD1/BRCA2 gene. These included an IVS7 splice‐site mutation, which is strongly associated with early AML in homozygous or compound heterozygous carrier status in FA‐D1 patients. Myeloid leukemia cells from this patient have been maintained in culture for more than 1 year and have been designated as the SB1690CB cell line. Growth of SB1690CB is dependent on granulocyte macrophage colony stimulating factor or interleukin‐3. This cell line has retained its MMC sensitivity and has undergone further spontaneous changes in the spectrum of cytogenetic aberrations compared with the primary leukemia. This is the second AML cell line derived from an FA‐D1 patient and the first proof that malignant clones arising in FA patients can retain inherited MMC sensitivity. As FA‐derived malignancies are normally not very responsive to treatment, this implies there are important mechanisms of acquiring correction of the cellular FA phenotype that would explain the poor chemoresponsiveness observed in FA‐associated malignancies and might also play a role in the initiation and progression of cancer in the general population.

Constitutional sequence variation in the Fanconi anaemia group C (FANCC) gene in childhood acute myeloid leukaemia

Summary. The extent to which genetic susceptibility contributes to the causation of childhood acute myeloid leukaemia (AML) is not known. The inherited bone marrow failure disorder Fanconi anaemia (FA) carries a substantially increased risk of AML, raising the possibility that constitutional variation in the FA (FANC) genes is involved in the aetiology of childhood AML. We have screened genomic DNA extracted from remission blood samples of 97 children with sporadic AML and 91 children with sporadic acute lymphoblastic leukaemia (ALL), together with 104 cord blood DNA samples from newborn children, for variations in the Fanconi anaemia group C (FANCC) gene. We found no evidence of known FANCC pathogenic mutations in children with AML, ALL or in the cord blood samples. However, we detected 12 different FANCC sequence variants, of which five were novel to this study. Among six FANCC variants leading to amino‐acid substitutions, one (S26F) was present at a fourfold greater frequency in children with AML than in the cord blood samples (odds ratio: 4·09, P = 0·047; 95% confidence interval 1·08–15·54). Our results thus do not exclude the possibility that this polymorphic variant contributes to the risk of a small proportion of childhood AML.

Modeling HLA associations with EBV-positive and -negative Hodgkin lymphoma suggests distinct mechanisms in disease pathogenesis

HLA genotyping and genome wide association studies provide strong evidence for associations between Human Leukocyte Antigen (HLA) alleles and classical Hodgkin lymphoma (cHL). Analysis of these associations is complicated by the extensive linkage disequilibrium within the major histocompatibility region and recent data suggesting that associations with EBV‐positive and EBV‐negative cHL are largely distinct. To distinguish independent and therefore potentially causal associations from associations confounded by linkage disequilibrium, we applied a variable selection regression modeling procedure to directly typed HLA class I and II genes and selected SNPs from EBV‐stratified patient subgroups. In final models, HLA‐A*01:01 and B*37:01 were associated with an increased risk of EBV‐positive cHL whereas DRB1*15:01 and DPB1*01:01 were associated with decreased risk. Effects were independent of a prior history of infectious mononucleosis. For EBV‐negative cHL the class II SNP rs6903608 remained the strongest predictor of disease risk after adjusting for the effects of common HLA alleles. Associations with “all cHL” and differences by case EBV status reflected the subgroup analysis. In conclusion, this study extends previous findings by identifying novel HLA associations with EBV‐stratified subgroups of cHL, highlighting those alleles likely to be biologically relevant and strengthening evidence implicating genetic variation associated with the SNP rs6903608.

Germline mutations and polymorphisms in the NFKBIA gene in Hodgkin lymphoma

Somatic inactivation of NFKBIA, the gene encoding IκBα, is a frequent occurrence in the malignant Hodgkin and Reed‐Sternberg (HRS) cells of Hodgkin lymphoma (HL). Impairment of IκBα function results in deregulated NF‐κB activity, a characteristic of HRS cells. The molecular basis for familial HL, which accounts for approximately 4% of all HL cases, is unclear. To date, familial HL cases have not been evaluated for germline NFKBIA mutations. We screened the entire NFKBIA gene in 8 individuals with familial HL but found no mutations in the coding region or promoter sequences. We identified the first germline NFKBIA missense mutation in a patient with presumed sporadic HL. The frequency of 4 polymorphisms within the NFKBIA gene and promoter region was investigated in a series of HL and control samples; no significant differences emerged but a novel polymorphism was identified in the promoter region. Overall, our results suggest that germline mutations of NFKBIA are not a significant cause of familial aggregation of HL but may contribute to inherited susceptibility to HL.

SECONDARY LEUKEMIA IN A CHILD WITH NEUROBLASTOMA WHILE ON ORAL ETOPOSIDE: What is the Cause?

To date little has been reported about the risk of therapy-related leukaemia (t-AML) in children receiving oral etoposide therapy. The authors present a case of t-AML that developed in a child with metastatic neuroblastoma 18 months after he received oral etoposide, given for palliation purpose. The leukemic blasts were examined by morphological, immunohistochemical, cytogenetic, and molecular genetic analyses. Although the t-AML developed following oral etoposide therapy, the child had previously received high-dose, multiagent chemotherapy, and rearrangement of the MLL gene was not demonstrated. The use of modern multiagent therapy often makes it difficult to appropriately apportion blame for causation of specific side effects. Moreover, the etiology of t-AML and mechanism of leukemogenesis are likely to be multifactorial and complex. Further studies on the precise association with different therapies are thus needed. Oral etoposide remains an effective palliative agent and its usage should not be excluded without most careful consideration of the risks.

Spectrum and significance of variants and mutations in the Fanconi anaemia group G gene in children with sporadic acute myeloid leukaemia

Childhood acute myeloid leukaemia (AML) is uncommon. Children with Fanconi anaemia (FA), however, have a very high risk of developing AML. FA is a rare inherited disease caused by mutations in at least 12 genes, of which Fanconi anaemia group G gene (FANCG) is one of the commonest. To address to what extent FANCG variants contribute to sporadic childhood AML, we determined the spectrum of FANCG sequence variants in 107 children diagnosed with sporadic AML, using polymerase chain reaction (PCR), fluorescent single‐strand conformational polymorphism (SSCP) and sequencing methodologies. The significance of variants was determined by frequency analysis and assessment of evolutionary conservation. Seven children (6·5%) carried variants in FANCG. Two of these carried two variants, including the known IVS2 + 1G>A mutation with the novel missense mutation S588F, and R513Q with the intronic deletion IVS12‐38 (‐28)_del11, implying that these patients might have been undiagnosed FA patients. R513Q, which affects a semi‐conserved amino acid, was carried in two additional children with AML. Although not significant, the frequency of R513Q was higher in children with AML than unselected cord bloods. While FANCG mutation carrier status does not predispose to sporadic AML, the identification of unrecognised FA patients implies that FA presenting with primary AML in childhood is more common than suspected.

Relationship between HLA‐DP supertype and survival in childhood acute lymphoblastic leukaemia: evidence for selective loss of immunological control of residual disease?

We recently reported that two of six HLA‐DP supertypes (DP1–4, 6, 8) were associated with susceptibility (DP2) and resistance (DP1) to childhood acute lymphoblastic leukaemia (ALL). To determine whether DP supertypes are associated with childhood ALL prognosis, we compared treatment outcomes in a cohort (n = 798) of DPB1‐typed ALL cases in the UK Medical Research Council UKALL XI trial. No differences in clinical characteristics and outcome between DPB1‐typed and untyped (n = 1292) cases suggest no selection bias. Event‐free survival (EFS) rates in patients with DP1 and DP3 supertypes were significantly worse than in patients with DP2, DP4, DP6 and DP8 [10‐year EFS: 55%; 95% confidence interval (CI) = 49–61%; compared with 64% (61–68%), P = 0·006]. Ten‐year EFS in DP1/DP3 heterozygous patients [30% (2–58%)] was significantly worse than in patients with DP1, DP3 or neither allele [56% (50–62%); P = 0·02]. Lack of evidence that DP1 or DP3 are associated with known prognostic factors leads us to suggest that these two supertypes exert an independent effect on prognosis. This may involve abrogation of DP1/3‐restricted T‐cell control of residual disease due to selective effects of chemotherapy. Further studies of HLA supertypes in relation to outcome in recent childhood ALL trials may resolve this question.