Etiological heterogeneity in Hodgkin's disease: HLA linked and unlinked determinants of susceptibility independent of histological concordance

The association of HLA-class I and class II with Hodgkin's lymphoma in Iranian patients

The Hodgkin's lymphoma disease (HD) is a common malignant neoplasm with germinal centre B-cell origin. It has been suggested that the HLA class I and class II regions have susceptibility effects on HD. In different ethnic groups, different HLA class I and class II alleles affect HD. As a result, there is no consensus which of the different HLA alleles confers susceptibility to HD. In this study, we aimed to ascertain the role of HLA class I and class II alleles in association with Hodgkin's lymphoma in Iranian patients. We performed a case-control genotyping study in 85 Iranian HD patients which were selected from the Bone Marrow Transplantation Department of Taleghani Hospital and 150 controls using the SSP-PCR. Our results demonstrated that the HLA-A*68, HLA-B*51, and HLA-DRB1*15 alleles were significantly more frequent in HD patients in comparison to controls (P = 0.026; OR = 6.188, P = 0.00008; OR = 2.86, P = 0.00006; OR = 5.315, resp.) and they have significant susceptibility effects on HD in Iranian population. There are reports of other populations with regard to consistency and inconsistency to our results. Further studies with large sample size or the meta-analysis are needed to explain the exact associations of HLA gene with HD.

Incidence and Characteristics of Childhood Hodgkin’s Lymphoma in Greece: A Nationwide Study (Greece)

OBJECTIVES

To estimate the incidence and epidemiological profile of childhood (0-14 years) Hodgkin's lymphoma in Greece derived by the network of childhood Hematology-Oncology departments on the basis of all 95 newly diagnosed cases during a seven-year period.

METHODS

Seventy-one of these cases were individually age and gender matched to an equal number of controls.

RESULTS

The incidence of childhood Hodgkin Lymphoma reached a relatively high figure of 7.8 per million children-years, with an age distribution (2.2 for children 0-4; 6.3 for those 5-9 and 13.9 for those 10-14-years-old) and male to female ratio (1.7:1) similar to that reported from other cancer registries. Childhood Hodgkin's lymphoma was more common among children living in less crowded quarters (odds ratio (OR): 6.5 and 95% confidence intervals (95% CI): 1.4-30.7), among those who have changed residence 60 to 18 months before the onset of the index disease (OR: 4.4, and 95% CI = 1.4-14.0), among those whose families owned a cat (OR: 5.5, 95% CI = 1.2-25.6) but not among those whose families owned a dog and marginally more common, among those with a history of infectious mononucleosis (OR: 5.0, 95% CI = 0.6-42.8).

CONCLUSIONS

Our results point to infectious agent(s) as playing an etiological role but do not allow discrimination among the delayed establishment of the herd immunity hypothesis, the population mixing hypothesis or that invoking transmission of the agent(s) from the non-human reservoir.

Genetic susceptibility to Hodgkin's lymphoma associated with the human leukocyte antigen region

Based on the presence of an abundant inflammatory infiltrate, expression of a broad spectrum of cytokines and the professional antigen presenting phenotype of Hodgkin Reed-Sternberg cells it can be anticipated that immunological mechanisms play a major role in the pathogenesis of Hodgkin's lymphoma (HL). Genetic susceptibility to HL probably relates to functionality of the immune system and the large number of associations with the human leukocyte antigen (HLA) region in family and population-based studies supports this relation. In Epstein-Barr virus (EBV) positive HL cases, which usually demonstrate HLA class I expression, HRS cells should be able to present EBV derived antigenic peptides and trigger the immune system. This process depends on the affinity of the HLA binding groove for binding immunogenic peptides and thus on the HLA alleles. It can be anticipated that certain combinations of alleles predispose to or protect from the development of EBV positive HL. In EBV negative HL cases other antigenic peptides, related to malignant transformation, in combination with other HLA alleles may be involved. In addition, differential attraction and activation of inflammatory cells may influence HL subtype. In this article, possible roles of HLA in HL pathogenesis are explored and genetic associations of HLA with HL are reviewed and commented on.

Germline mutations and polymorphisms in the NFKBIA gene in Hodgkin lymphoma

Somatic inactivation of NFKBIA, the gene encoding IkappaBalpha, is a frequent occurrence in the malignant Hodgkin and Reed-Sternberg (HRS) cells of Hodgkin lymphoma (HL). Impairment of IkappaBalpha function results in deregulated NF-kappaB 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.

The genetics of familial lymphomas

Whereas familial clustering of malignant lymphoma is well documented, the molecular changes underlying familial lymphoma syndromes remain unclear. An understanding of the hereditary basis of lymphoma may lead to the identification of new molecular markers for disease or novel therapeutic targets. This paper reviews the genetics of familial lymphoma, focusing on germline susceptibilities to lymphoma as well as germline susceptibilities to environmental exposures that have been linked to lymphoma.

HLA-DR, HLA-DQ, and TAP genes in familial Hodgkin disease

The HLA region has long been implicated in sporadic and familial Hodgkin disease (HD), with recent case-control studies suggesting that HLA class II loci predispose to sporadic nodular sclerosis HD (NSHD). To determine whether this predisposition extends to familial HD, HLA class II loci (DRB1, DQA1, DQB1, DRB3, DRB4, and DRB5) and transporter associated with antigen processing (TAP) loci (TAP1, TAP2) were investigated in 100 members of 16 families with at least 2 confirmed cases of HD. With the use of the transmission disequilibrium test, evidence for linkage disequilibrium with familial HD and, in particular, familial NSHD was obtained for the DRB1*1501-DQA1*0102-DQB1*0602 haplotype, the TAP1 allele encoding Ile at residue 333, and the DRB5-0101 allele. These 3 markers were in linkage disequilibrium and may not represent independent susceptibility regions. Use of a family-based approach excludes population stratification as an explanation for these findings.

Pseudoautosomal linkage of Hodgkin disease

Heritable factors appear to account for much of the risk for Hodgkin disease (HD). There is evidence for an HLA-linked gene, but other predisposing loci remain unaccounted for. The observation of a family coinheriting both HD and Leri-Weill dyschondrosteosis (LWD) suggests that a gene conferring risk for HD resides adjacent to the LWD locus. The gene responsible for LWD, SHOX, localizes to the short-arm pseudoautosomal region (PAR) of the X and Y chromosomes. A unique segregation pattern for PAR-linked genes has been predicted-that affected sibs will tend to be same sex. An excess of sex-concordant affected sib pairs with HD has been noted but has been attributed to an environmental etiology. These two observations-sex concordance in sib pairs with HD and cosegregation of HD and LWD-impelled a test of the hypothesis that there is a PAR-localized gene for HD. By first scoring recombinations dissociating sex from phenotype in individuals from pedigrees with LWD, we determined a male maximum recombination frequency (thetamax) of.405. This places SHOX near the short-arm telomeres of the sex chromosome and supports the prediction that PAR recombination is obligatory for spermatogenesis. By inferring recombinations between HD and sexual phenotype in sib pairs, we predict, for the postulated HD gene, a male thetamax as high as .254, which places it in proximity to SHOX. Morton's nonparametric affected-sib-pair "beta" model was used in the evaluation of linkage between HD and phenotypic sex and gave a LOD score of 2.41. Using this approach, we reevaluated evidence for HLA linkage in HD in haplotyped sib pairs and found a LOD score of 2.00. The resulting beta values indicate that the putative PAR- and HLA-linked loci account for 29% and 40%, respectively, of the heritability of HD in an American population.

Concordance for Hodgkin's disease in identical twins suggesting genetic susceptibility to the young-adult form of the disease

BACKGROUND

Relatives of young adults with Hodgkin's disease are at increased risk of Hodgkin's disease, and lines of evidence implicate both inheritance and environment.

METHODS

We have identified and followed 432 sets of twins affected by Hodgkin's disease. The number of cases of Hodgkin's disease observed before the age of 50 years in the healthy monozygotic and dizygotic twins of the patients with Hodgkin's disease was compared with the number expected from national age-specific incidence rates.

RESULTS

None of the 187 pairs of dizygotic twins became concordant for Hodgkin's disease, whereas 10 of the 179 pairs of monozygotic twins did; in 5 of these pairs, the second case appeared after the original ascertainment. During the observation period, 0.1 (monozygotic) and 0.1 (dizygotic) cases in the unaffected twins were expected. Monozygotic twins of patients with Hodgkin's disease thus had a greatly increased risk (standardized incidence ratio, 99; 95 percent confidence interval, 48 to 182), whereas no increase in the risk for dizygotic twins of patients with Hodgkin's was observed.

CONCLUSIONS

Genetic susceptibility underlies Hodgkin's disease in young adulthood.