te Gerhardus Meerman

Association with HLA class I in Epstein-Barr-virus-positive and with HLA class III in Epstein-Barr-virus-negative Hodgkin's lymphoma.

BACKGROUND Associations of Hodgkins lymphoma with HLA have been reported for many years. In 20-40% of patients with this disorder, Epstein-Barr virus (EBV) is present in the neoplastic cells. Because presentation of EBV antigenic peptides can elicit vigorous immune responses, we investigated associations of the HLA region with EBV-positive and EBV-negative Hodgkins lymphoma. METHODS In a retrospective, population-based study, patients with Hodgkins lymphoma were reclassified according to the WHO classification, and EBV status was assessed by in-situ hybridisation of EBV-encoded small RNAs. Germline DNA was isolated from 200 patients diagnosed between 1987 and 2000 and from their first-degree relatives. Genotyping was done with 33 microsatellite markers spanning the entire HLA region and two single-nucleotide polymorphisms in the genes for tumour necrosis factor alpha and beta. Classic association analysis and the haplotype sharing statistic were used to compare patients with controls. FINDINGS Classic association analysis (but not the haplotype sharing statistic) showed an association of consecutive markers D6S265 and D6S510 (p=0.0002 and 0.0003), located in the HLA class I region, with EBV-positive lymphomas. The haplotype sharing statistic (but not classic association analysis) showed a significant difference in mean haplotype sharing between patients and controls surrounding marker D6S273 (p=0.00003), located in HLA class III. INTERPRETATION Areas within the HLA class I and class III regions are associated with susceptibility to Hodgkins lymphoma, the association with class I being specific for EBV-positive disease. This finding strongly suggests that antigenic presentation of EBV-derived peptides is involved in the pathogenesis of EBV-involved Hodgkins lymphoma. RELEVANCE TO PRACTICE Polymorphisms in the HLA region could explain ethnic variation in the incidence of Hodgkins lymphoma. The association of EBV-positive Hodgkins lymphoma with HLA class I suggests that this polymorphism might affect the proper presentation of EBV antigens to cytotoxic T lymphocytes.

Perspectives of identity by descent (IBD) mapping in founder populations

In a founder population patients with a genetic disease are likely to share predisposing genes from a common ancestor. We show that, depending on the distance of the relationship, patients are expected to share extended segments of DNA around the disease gene. Because of the size of the shared segment, a genomic search with DNA markers for such shared segments, identity by descent (IBD) mapping, can efficiently find the map position of genes, particularly due to genetic drift leading to reduction of heterogeneity and the large number of meioses that is implicitly observed. The statistical power of this method and the approximate cost are given as a function of the density of the map of tested markers and the number of generations since a common ancestor. Initial marker spacings between 5 and 15 centiMorgans are shown to be optimal. IBD mapping is applicable to many genetic diseases, because it does not presuppose a specific genetic model.

Susceptibility to development of Mycobacterium ulcerans disease: review of possible risk factors

Mycobacterium ulcerans disease, also known as Buruli ulcer (BU), is a disease of subcutaneous fat tissue. BU is prevalent in riverine and swamp areas of the tropical zone in Africa, Asia and South America, and a few scattered foci in Australia. The mode of transmission of M. ulcerans has not been fully elucidated, but inoculation into the subcutaneous tissues probably occurs through penetrating skin trauma. BU has not been linked with HIV infection. Antimycobacterial drug treatment is ineffective, and treatment is surgical. Patients eventually develop scars and contractures, with resulting disabilities, and the disease imposes a large burden on affected populations. The incidence of BU has dramatically increased in West African countries over the last decade. There is an urgent need for research into host and environmental risk factors for BU in order to develop effective strategies to combat this disease. We review possible genetic host susceptibility factors for BU that are relevant in other mycobacterial diseases: natural resistance‐associated macrophage protein‐1 (NRAMP‐1), HLA‐DR, vitamin D3 receptor, mannose binding protein, interferon‐gamma (IFN‐γ) receptor, tumour necrosis factor alpha (TNF‐α), interleukin (IL)‐1α, 1β and their receptor antagonists; and IL‐12. Schistosoma haematobium infection is highly endemic in many BU foci in West Africa, with a striking increase in transmission after river dams were constructed. This observation, and the observations from interaction of schistosomiasis and tuberculosis, have fuelled our hypothesis that schistosomiasis is a risk factor for BU by driving the host immune response towards a predominantly Th‐2 pattern, away from a Th‐1 preponderant protection against mycobacterial infection. If the latter hypothesis is confirmed, enhanced schistosomiasis control should impact on BU.

Analysis of the entire HLA region in susceptibility for cervical cancer: a comprehensive study

Background: Infection with human papillomavirus (HPV) is the main cause of cervical cancer and its precursor lesion, cervical intraepithelial neoplasia (CIN). Variability in host immunogenetic background is important in determining the overall cellular immune response to HPV infections. Objective: To determine whether the HLA-DQ or HLA-DR genes, or others in their vicinity, are associated with cervical cancer. Methods: Markers covering the entire HLA region were genotyped in a large sample of CIN and cervical cancer patients and in controls (311 CIN, 695 cervical cancer, 115 family controls, and 586 unrelated controls). Results: Two markers were associated with susceptibility to cervical neoplasia, G511525 and MICA. G511525, close to the region containing the HLA-DQ and HLA-DR genes, was most strongly associated, showing a decrease in frequency of allele 221 from 6.7% to 3.3% in patients with squamous cell cancer (SCC). An association was found for MICA (allele 184) with SCC (odds ratio (OR) = 1.31 (95% confidence interval, 1.13 to 1.53); homozygotes, OR = 1.48 (1.06 to 2.06)). No associations were observed with adenocarcinoma or CIN. Conclusions: There is an association of the region containing the HLA-DQ and HLA-DR genes with the risk of developing squamous cell carcinoma. An increased risk was observed for carriers of allele 184 at the MICA locus, in particular for homozygotes, suggesting a recessive effect.

Immunohistochemical changes induced by repeated footshock stress: revelations of gender-based differences

As a growing literature has proven, adverse experiences, particularly when severe and persistent, play a pivotal role in the development of neuronal dysfunctions and psychopathology. In the present study, the neurochemical changes induced by acute and repeated footshock exposure were investigated at the molecular and cellular level, using c-fos and phospho-ERK1/2 immunoreactivity and gene expression arrays. Marked gender-related differences were found following both acute and prolonged footshock exposure. Acute aversive conditioning resulted in significant immunohistochemical changes that might be critically involved in the modulation of fear-related responses, especially in males. Prolonged footshock exposure, on the contrary, was associated with sustained hypothalamic-pituitary-adrenal axis hyperactivity, differential gender-related patterns of cortical-limbic activity, and abnormal neuronal plasticity, especially in medial prefrontocortical regions. These data may provide additional insights into the understanding of the neural circuits underlying the effects of acute and repeated footshock exposure as well as clarify some of the mechanisms involved in the development of stress-related neuronal abnormalities.

Genomic sharing surrounding alleles identical by descent: Effects of genetic drift and population growth

The number of identical deleterious mutations present in a population may become very large, depending on the combined effect of genetic drift, population growth and limited negative selection. The distribution of the length of the shared area between two random chromosomes carrying the mutations has been investigated for a number of generations varying from 20-100 since introduction. The consequences for investigations using association and haplotype sharing methods are discussed

Family Distances and Human Lymphocyte Antigens

We compared family distances of homozygotes and heterozygotes for HLA-A and -B. When matched on number of inhabitants per birthplace, no significant differences were found. However, when homozygotes were compared with heterozygotes from larger birthplaces, homozygotes showed significantly smaller family distances in the grandparental generation. We suggest that matching for population size of birthplace and the choice of the geographic study area are important factors in studies of family distances.

Effect of screening for cystic-fibrosis on the influence of genetic-counseling

We studied the influence of genetic counseling for cystic fibrosis on family planning, using neonatal screening, family size at time of diagnosis, and maternal age as possible determinants for reproductive behaviour. The expected number of children born to mothers of equal age and parity in the same period was approximated on the basis of population statistics. These numbers were compared to the numbers of children born in the study group after a CF diagnosis and information on the 25% recurrence risk were given. A 50.8% reduction in childbirth was found in the study group, although 77% of families had decided against further high‐risk pregnancies. No statistically significant influence of neonatal screening could be demonstrated, but this may be due to the small number of families involved.

An extensive screen of the HLA region reveals an independent association of HLA class I and class II with susceptibility for systemic lupus erythematosus

Objectives: The association of systemic lupus erythematosus (SLE) with the human leucocyte antigen (HLA) region is well known. In this study, we analysed the involvement of the HLA region in susceptibility for SLE in a stable founder, Caucasian population of SLE patients. Methods: We performed an extensive screen of the entire HLA region on 103 SLE patients and family‐based controls. Both single locus association analysis and haplotype sharing analysis were performed. The Additional Disease Locus Test (ADLT) was applied to examine the nature of the observed associations and to distinguish true causal associations from associations due to linkage disequilibrium (LD). Results: Significant associations were observed at markers in the HLA class I, class II, and class III regions using both haplotype sharing and single locus methods. The haplotype sharing methods revealed the most significant difference at marker D6S1666 in the HLA class II region (pHSS = 0.00037, pCROSS = 1.7 × 10−5). The most significant result for single locus association was shown at marker D6S265 in the HLA class I region (p = 0.00019). The ADLT demonstrated that these markers represent independent associations. Conclusion: HLA class I, class II, and class III are associated with SLE, but only class I and class II contribute independently to increased risk of SLE.

SCREENING FOR CYSTIC-FIBROSIS : A COMPARATIVE-STUDY

ABSTRACT. A neonatal screening program for CF by determination of albumin in meconium was performed in the north eastern part of the Netherlands from 1973 to 1979. In this period 94043 newborns were screened and 116953 were not. A follow‐up study of CF patients in the above cohorts was started in 1980. The purposes of this study were to evaluate the effects of early diagnosis and treatment in CF patients by comparing the outcome in the two groups of patients. Although the results indicate that very early diagnosis and treatment have a beneficial effect on outcome, more studies are needed before a definite answer can be given as to whether or not mass neonatal screening should be started.