Amount of DNA in plasma and cancer risk: a prospective study

Levels of plasma DNA concentrations in cancer patients have been shown to be higher than the plasma DNA concentrations found in healthy subjects. The value of plasma DNA levels for development of neoplastic or pulmonary disease was evaluated in a large prospective study. Plasma samples (n = 1,184) were analyzed from 776 controls, 359 cases of cancer (lung, bladder, oral cavity, pharynx, larynx, leukemia) and 49 deaths from chronic obstructive pulmonary disease (COPD), including never smokers and ex-smokers, from 9 countries across Europe. The amount of plasma DNA was variable across the European Prospective Investigation into Cancer and Nutrition (EPIC) centers. High DNA concentrations in some centers might be due to the type of population recruited and/or the treatment of the samples. An elevated and statistically significant odds ratio (OR) was found for COPD deaths (OR = 2.53; 95% CI = 1.06-6.02), while nonsignificant increased ORs were present for oral cancers, cancers of the pharynx and larynx and leukemia. When the analyses were stratified by time since recruitment (below or above 36 months), the increased ORs were limited to the more recent period of recruitment, i.e., a time elapsed between blood drawing and disease onset lower than 36 months. This was particularly true for COPD deaths (OR = 12.7; 95% CI = 1.57-103) and leukemia (OR = 2.37; 95% CI = 1.20-4.67).

Interaction between gene polymorphisms of nitric oxide synthase and renin-angiotensin system in the progression of membranous glomerulonephritis

BACKGROUND

The renin-angiotensin system (RAS) and nitric oxide synthase (NOS) play a key role in the progression of primary glomerulonephritis (GN). Although previous studies have examined genetic risk associated with single gene variations, experiments assessing risk conferred by multiple gene variations are still scanty.

METHODS

The effect of combination of variant alleles of four genes encoding for three components of the RAS [angiotensin converting enzyme insertion/deletion (ACE I/D), angiotensin II receptor 1 (AT1R 1166A/C), angiotensinogen (AGT M235T)] and for NOS (ecNOS4b/a) on the development and progression of membranous GN (MGN) were evaluated in a longitudinal study comparing 117 patients with serum creatinine (s-Cr) <1.5 mg/dl at renal biopsy and follow-up > or = 5 years (Kaplan-Meier and Cox multivariate analysis). The control group consisted of DNA from 171 organ donors.

RESULTS

We found no relationship between single or combined variations of the four gene polymorphisms and development of MGN. Among single gene variations, there were no independent genetic risk factors for the progression of renal disease, after adjustment for age, sex, hypertension, proteinuria, s-Cr, chronicity and activity index. However, double variation coincidences such as the combination of the allele a of ecNOS4b/a and both the allele D of ACE I/D (chi(2) =4.80, P = 0.028; HR = 1.97, 95% CI 0.98-3.96) and the allele T of AGT (M235T) (chi(2) = 5.09, P = 0.024; HR = 2.84, 95% CI 1.39-5.82) exerted an additional effect that was higher than that of the single gene variations.

CONCLUSION

This study is the first to demonstrate a role for an interaction between simultaneous variations of genes encoding for NOS and components of RAS in the progression of MGN. Interactions between various polymorphisms may explain conflicting results obtained in previous studies that examined single gene variations, since the effect of a single locus variation may be influenced by the simultaneous presence of other variant alleles in polygenic diseases such as primary GN. However, the small sample sizes and possible multiple interactions limited the interpretation of the current findings, which may represent true biological interaction or simply statistical interactions or spurious results due to the small sample sizes.

Ras gene mutations in patients with acute myeloid leukaemia and exposure to chemical agents

Mutations of the N- and K-ras genes occur in approximately 15-30% of acute myeloid leukaemia patients. The role of the oncogenic ras in leukaemogenesis remains unclear. Few studies have revealed that mutations in the ras oncogene family are more probably found in acute myeloid leukaemia patients with previous exposure to toxic agents. A case-case study was conducted in the areas of Florence and Turin, Italy, to investigate whether the presence of N- and K-ras mutations in acute myeloid leukaemia patients was related to a higher frequency of exposure to chemicals. During a 3-year period, 111 acute myeloid leukaemia patients were enrolled. All the patients were interviewed using a semi-structured questionnaire collecting data on residential history, occupation, personal habits and pathological history. The presence of N- and K-ras mutations was analysed by amplification and synthetic oligonucleotide probes and by the so-called polymerase chain reaction amplification for specific alleles technique. A total of 34 (30.6%) patients were found to harbour ras mutations in N-ras and/or K-ras. Fourteen patients (12.6%) had a single ras mutation and 20 patients (18%) had two ras mutations. A positive association between a priori at risk jobs and ras mutations was found, based on nine exposed cases; the odds ratio, adjusted by age, sex and previous X-ray and/or chemotherapy was 2.8 (95% confidence intervals: 0.9-9.0). When considering only subjects with two ras mutations the odds ratio was 4.8 (95% confidence intervals: 1.2-18.8). The odds ratio for a previous X-ray and/or chemotherapy was 16.2 (95% confidence intervals: 1.8-755.9); when only subjects with two ras mutations were considered, the odds ratio was 26.1 (95% confidence intervals: 2.5-1248.9). In conclusion, our data suggest that ras oncogene mutations might identify a group of leukaemia in people with previous X-ray/chemotherapy or with exposure to chemical agents in the work environment.

Estrogen receptor-alpha polymorphisms and angiographic outcome after coronary artery stenting

OBJECTIVE

Because of the receptor-mediated antiproliferative effects of estradiol on vascular smooth muscle cells, our study aimed at identifying a role of PvuII and XbaI polymorphisms of the alpha-estrogen receptor (alphaER) gene in the occurrence of restenosis after coronary stent implantation (in-stent restenosis [ISR]).

METHODS AND RESULTS

In 858 patients (148 women), 955 lesions were treated with stent implantation, and the PvuII C/T and XbaI G/A polymorphisms of the alphaER gene were determined. Quantitative angiography was performed before and after stenting and at 6-month follow-up. The allelic frequencies were similar between sexes (C/T allele, 0.43/0.57 and 0.44/0.56; P=0.9; G/A allele, 0.35/0.65 and 0.38/0.62; P=0.8; in women and men, respectively). A significantly higher ISR rate in women than in men homozygous for the T-allele of the PvuII polymorphism (42.6% versus 26.9%, P=0.03) or the G-allele of the XbaI polymorphism (41.2% versus 19.4%, P=0.04) was observed. At multivariate analysis, T/T genotype was the only independent predictor of ISR in women but not in men (odds ratio, 1.5; 95% CI, 1.0 to 2.1; P=0.03). XbaI polymorphism was no longer associated with ISR in both sexes.

CONCLUSIONS

Women homozygous for the T-allele of the PvuII polymorphism of the alphaER gene treated with coronary stent implantation have a higher risk of ISR than men.

Combination of DNA repair gene single nucleotide polymorphisms and increased levels of DNA adducts in a population-based study

Inherited single nucleotide polymorphisms (SNPs) of DNA repair genes may contribute to variations in DNA repair capacity and susceptibility to cancer. We investigated the role of SNPs in three DNA repair genes (X-ray repair cross-complementing group 1-Arg399Gln, exon 10; X-ray repair cross-complementing group 3-Thr241Met, exon 7; and xeroderma pigmentosum-D-Lys751Gln, exon 23) and their combination, in modulating the levels of "bulky" DNA adducts in a population sample of 628 Italian healthy individuals belonging to the prospective European project "European Prospective Investigation into Cancer and Nutrition." DNA-adduct levels were measured as relative adduct level per 10(9) nucleotides by (32)P-post DNA labeling assay in WBCs from peripheral blood. Genotyping was performed by PCR-RFLP analysis or primer extension/denaturing high-performance liquid chromatography technique. We found a dose-response relationship between the number of at-risk alleles and levels of adducts (P = 0.0046). Individuals with at least three variant alleles had a statistically significant odds ratio (OR) for being in the highest tertile of adducts compared with those with undetectable adducts [three alleles, adjusted OR = 5.07, 95% confidence interval (CI) = 1.29-19.9; four alleles, adjusted OR = 5.03, 95% CI = 1.18-21.45; five alleles, adjusted OR = 7.65, 95% CI = 0.94-62.2]. Our study suggests that the combined effect of multiple variant alleles may be more important than the investigation of single SNP in modulating DNA repair capacity.

Bulky DNA adducts and risk of cancer: a meta-analysis

We present a meta-analysis to test the hypothesis that the presence of a high level of bulky DNA adducts in tissues is associated with an increased risk of cancer in humans. Seven articles were selected that matched the selection criteria, for a total of 691 cancer patients and 632 control subjects. In five studies the cases had lung cancer, in one oral cancer, and in one bladder cancer. Six studies measured adducts in WBCs and one in normal lung tissue around tumor tissue. Six were case-control investigations, and one was a case-control study on lung cancer nested within a cohort. Current smokers showed a statistically significant difference between cases and controls, with cases having 83% higher levels of adducts than controls (95% confidence interval, 0.44-1.22). Results were negative or contradictory in ex-smokers and nonsmokers. This observation was confirmed by sensitivity analyses. Publication bias does not seem to be a problem. Despite some methodological limitations, our meta-analysis shows that current smokers with high levels of adducts have an increased risk of lung and bladder cancers. This conclusion also suggests that similar (aromatic) compounds may be involved in the etiology of both types of cancer.

An evolutionary paradigm for carcinogenesis?

Mutations seem to be only one of the mechanisms involved in carcinogenesis; selection of mutated clones is a second crucial mechanism. An evolutionary (darwinian) theory of carcinogenesis can be useful to explain some contradictory observations of epidemiology, and to provide a common theoretical framework for carcinogenesis. In both the selection of species and in carcinogenesis (selection of mutated cells), mutation and selection can be interpreted as necessary and insufficient causes. Selection presupposes competition among clones-that is, survival advantage of the mutated species; without selective forces a mutation is mute, while the lack of mutations makes selective advantage impossible. The identification of carcinogen related fingerprints is ambiguous: it can suggest both a genuine mutational hotspot left by the carcinogenic stimulus (like in tobacco related p53 mutations), and selective advantage of clones whose mutations seem to be not exposure specific (like in the case of aflatoxin). We present several examples of exposures that can increase the risk of cancer in humans not via mutations but through a putative mechanism of clone selection.

Effect of angiotensin-converting enzyme inhibition on restenosis after coronary stenting

The Plasma level of angiotensin-converting enzyme (ACE) has been identified as a major risk factor for restenosis after coronary stent implantation in selected patients; ACE inhibition may therefore contribute to prevent its occurrence. The effect of oral ACE inhibition at conventional doses was analyzed retrospectively in a series of 897 patients with ischemia who received >or=1 coronary stent on 998 lesions and underwent angiographic follow-up; no exclusion criteria were introduced in this analysis. The restenosis rate in 282 patients (31.4%) taking ACE inhibitors was 36.6% compared with 22.9% in 615 non-ACE-inhibited patients (p = 0.00001, odds ratio [OR] 1.94, 95% confidence interval [CI] 1.45 to 2.59), and the late loss in minimum lumen diameter was 1.25 +/- 0.8 versus 0.96 +/- 0.8 mm, respectively (p = 0.0001). During univariate analysis, a negative effect of the drug on restenosis was observed in all subgroups of patients (i.e., hypertensives, diabetics, women, and patients with previous myocardial infarction). Similar effects were observed independently of the ACE gene insertion/deletion polymorphism. During multivariate analysis, ACE inhibition was confirmed as an independent risk factor for restenosis (OR 1.84, 95% CI 1.35 to 2.51, p = 0.0001). Other predictors were the implantation of multiple stents (OR 2.41, 95% CI 1.60 to 3.64, p <0.0001), diabetes (OR 2.34, 95% CI 1.61 to 3.41, p <0.0001), and vessel reference diameter before angioplasty (OR 0.51, 95% CI 0.38 to 0.69, p <0.0001). Although unexplained and apparently contradictory, our data suggest that the use of conventional oral doses of ACE inhibitors in a "real-world" population who underwent coronary stent implantation increases the incidence of in-stent restenosis. Such a finding does not negate the known clinical benefits of ACE inhibitors, but it may deserve attention when a patient treated with ACE inhibitors becomes a candidate for stent implantation.

Autosomal microsatellite and mtDNA genetic analysis in Sicily (Italy)

DNA samples from 465 blood donors living in 7 towns of Sicily, the largest island of Italy, have been collected according to well defined criteria, and their genetic heterogeneity tested on the basis of 9 autosomal microsatellite and mitochondrial DNA polymorphisms for a total of 85 microsatellite allele and 10 mtDNA haplogroup frequencies. A preliminary account of the results shows that: a) the samples are genetically heterogeneous; b) the first principal coordinates of the samples are correlated more with their longitude than with their latitude, and this result is even more remarkable when one outlier sample (Butera) is not considered; c) distances among samples calculated from allele and haplogroup frequencies and from the isonymy matrix are weakly correlated (r = 0.43, P = 0.06) but such correlation disappears (r = 0.16) if the mtDNA haplogroups alone are taken into account; d) mtDNA haplogroups and microsatellite distances suggest settlements of people occurred at different times: divergence times inferred from microsatellite data seem to describe a genetic composition of the town of Sciacca mainly derived from settlements after the Roman conquest of Sicily (First Punic war, 246 BC), while all other divergence times take root from the second to the first millennium BC, and therefore seem to backdate to the pre-Hellenistic period. A more reliable association of these diachronic genetic strata to different historical populations (e.g. Sicani, Elymi, Siculi), if possible, must be postponed to the analysis of more samples and hopefully more informative uniparental DNA markers such as the recently available DHPLC-SNP polymorphisms of the Y chromosome.

Haptoglobin phenotype and the risk of restenosis after coronary artery stent implantation

We recently demonstrated that an allelic polymorphism in the haptoglobin gene is a major determinant of susceptibility to a number of vascular disorders. We set out to determine if haptoglobin phenotype was predictive of the development of restenosis in a consecutive series of patients, all of whom underwent stent implantation followed by repeat angiography with quantitative coronary angiography analysis 6 months later. This study included 214 consecutive patients undergoing stent implantation for de novo lesions between 1998 and 1999 in Aalst, Belgium. All underwent follow-up quantitative coronary angiography analysis 6 months after the procedure. The haptoglobin phenotype was determined by electrophoresis. No significant differences were found between patients segregated by phenotype with respect to clinical, procedural, and angiographic factors previously suggested to influence the development of restenosis. None of the diabetic patients homozygous for the haptoglobin 1 allele developed restenosis compared with a >50% restenosis rate for diabetic patients with at least 1 haptoglobin 2 allele (p <0.02). In all patients (diabetic and nondiabetic), we observed a trend toward a lower incidence of restenosis in patients homozygous for the 1 allele (21% vs 33%, p <0.09). Moreover, we found a graded risk relation to the number of haptoglobin 2 alleles. The risk of developing restenosis was greater in subjects with 2 haptoglobin 2 alleles (36%) than in those with 1 haptoglobin 2 allele (31%) or no haptoglobin 2 alleles (21%). Thus, knowledge of the haptoglobin phenotype may be useful in assessing and utilizing new therapies that attempt to reduce restenosis, and may have important implications for the risk stratification algorithm used in managing diabetic patients with coronary artery disease.

DNA adduct levels and DNA repair polymorphisms in traffic-exposed workers and a general population sample

Peripheral blood DNA adducts have been considered an acceptable surrogate for target tissues and possibly predictive of cancer risk. A group of 114 workers exposed to traffic pollution and a random sample of 100 residents were drawn from the EPIC cohort in Florence, a population recently shown to present increased DNA adduct levels (Palli et al., Int J Cancer 2000;87:444-51). DNA bulky adducts and 3 DNA repair gene polymorphisms were analyzed in peripheral leukocytes donated at enrollment, by using (32)P-postlabeling and PCR methods, respectively. Adduct levels were significantly higher for traffic workers among never smokers (p = 0.03) and light current smokers (p = 0.003). In both groups, urban residents tended to show higher levels than those living in suburban areas, and a seasonal trend emerged with adduct levels being highest in summer and lowest in winter. Traffic workers with at least 1 variant allele for XPD-Lys751Gln polymorphism had significantly higher levels in comparison to workers with 2 common alleles (p = 0.02). A multivariate analysis (after adjustment for age, season, area of residence, smoking, XPD-Lys751Gln genotype and antioxidant intake) showed a significant 2-fold association between occupational exposure and higher levels of adducts (odds ratio 2.1; 95% confidence interval 1.1-4.2), in agreement with recent pooled estimates of increased lung cancer risk for similar job titles. Our results suggest that traffic workers and the general population in Florence are exposed to high levels of genotoxic agents related to vehicle emissions. Photochemical pollution in warmer months might be responsible for the seasonal trend of genotoxic damage in this Mediterranean urbanized area.

XRCC1, XRCC3, XPD gene polymorphisms, smoking and (32)P-DNA adducts in a sample of healthy subjects

DNA repair genes have an important role in protecting individuals from cancer-causing agents. Polymorphisms in several DNA repair genes have been identified and individuals with non-dramatic reductions in the capacity to repair DNA damage are observed in the population, but the impact of specific genetic variants on repair phenotype and cancer risk has not yet been clarified. In 308 healthy Italian individuals belonging to the prospective European project EPIC, we have investigated the relationship between DNA damage, as measured by (32)P-DNA adduct levels, and three genetic polymorphisms in different repair genes: XRCC1-Arg399Gln (exon 10), XRCC3-Thr241Met (exon 7) and XPD-Lys751Gln (exon 23). DNA adduct levels were measured as relative adduct level (RAL) per 10(9) normal nucleotides by DNA (32)P-post-labelling assay in white blood cells from peripheral blood. Genotyping was performed by PCR-RFLP analysis. The XRCC3-241Met variant was significantly associated with higher DNA adduct levels, whereas XRCC1-399Gln and XPD-751Gln were associated with higher DNA adduct levels only in never-smokers. XRCC3-241Met homozygotes had an average DNA adduct level of 11.44 +/- 1.48 (+/-SE) compared with 7.69 +/- 0.88 in Thr/Met heterozygotes and 6.94 +/- 1.11 in Thr/Thr homozygotes (F = 3.206, P = 0.042). Never-smoking XRCC1-399Gln homozygotes had an average DNA adduct level of 15.60 +/- 5.42 compared with 6.16 +/- 0.97 in Gln/Arg heterozygotes and 6.78 +/- 1.10 in Arg/Arg homozygotes (F = 5.237, P = 0.007). A significant odds ratio (3.81, 95% CI 1.02-14.16) to have DNA adduct levels above median value was observed for XPD-751Gln versus XPD-751Lys never-smoking homozygotes after adjustment for several confounders. These data show that all the analysed polymorphisms could result in deficient DNA repair and suggest a need for further investigation into the possible interactions between these polymorphisms, smoking and other risk factors.

DNA repair gene polymorphisms, bulky DNA adducts in white blood cells and bladder cancer in a case-control study

Individuals differ widely in their ability to repair DNA damage, and DNA-repair deficiency may be involved in modulating cancer risk. In a case-control study of 124 bladder-cancer patients and 85 hospital controls (urological and non-urological), 3 DNA polymorphisms localized in 3 genes of different repair pathways (XRCC1-Arg399Gln, exon 10; XRCC3-Thr241Met, exon 7; XPD-Lys751Gln, exon 23) have been analyzed. Results were correlated with DNA damage measured as (32)P-post-labeling bulky DNA adducts in white blood cells from peripheral blood. Genotyping was performed by PCR-RFLP analysis, and allele frequencies in cases/controls were as follows: XRCC1-399Gln = 0.34/0.39, XRCC3-241Met = 0.48/0.35 and XPD-751Gln = 0.42/0.42. Odds ratios (ORs) were significantly greater than 1 only for the XRCC3 (exon 7) variant, and they were consistent across the 2 control groups. XPD and XRCC1 appear to have no impact on the risk of bladder cancer. Indeed, the effect of XRCC3 was more evident in non-smokers [OR = 4.8, 95% confidence interval (CI) 1.1-21.2]. XRCC3 apparently interacted with the N-acetyltransferase type 2 (NAT-2) genotype. The effect of XRCC3 was limited to the NAT-2 slow genotype (OR = 3.4, 95% CI 1.5-7.9), suggesting that XRCC3 might be involved in a common repair pathway of bulky DNA adducts. In addition, the risk of having DNA adduct levels above the median was higher in NAT-2 slow acetylators, homozygotes for the XRCC3-241Met variant allele (OR = 14.6, 95% CI 1.5-138). However, any discussion of interactions should be considered preliminary because of the small numbers involved. Our results suggest that bladder-cancer risk can be genetically modulated by XRCC3, which may repair DNA cross-link lesions produced by aromatic amines and other environmental chemicals.

Acute myocardial infarction in young adults: prognostic role of angiotensin-converting enzyme, angiotensin II type I receptor, apolipoprotein E, endothelial constitutive nitric oxide synthase, and glycoprotein IIIa genetic polymorphisms at medium-term follow-up

BACKGROUND

A number of reports have investigated the association between various gene polymorphisms and the phenotypic expression of myocardial infarction. No investigations have evaluated the prognostic role of genetic factors in young people with premature coronary disease. The aim of this study was to investigate the influence of genetic factors compared with that of conventional risk factors on follow-up events in a population of Italian young adults with myocardial infarction.

METHODS AND RESULTS

The study population consisted of 106 young patients (mean age 40 +/- 4 years, range 23 to 45 years) with diagnosis of acute myocardial infarction. Clinical and genetic data from the group of patients with events during follow-up were compared with those from patients without events. The following genetic polymorphisms were tested: angiotensin I converting enzyme, angiotensin II type I receptor, apolipoprotein E (ApoE), endothelial constitutive nitric oxide synthase, and platelet glycoprotein IIIa. Coronary angiography was performed in 94 patients. Coronary angiography showed coronary artery disease in 93% of patients. During follow-up (46 +/- 12 months, range 25 to 72) the overall combined end points (cardiac death, myocardial infarction, and revascularization procedures) accounted for 21 events. Family history of coronary artery disease, smoking, stenosis of the left anterior descending artery at coronary angiography, and ApoE polymorphism (presence of epsilon4 allele) were significantly more prevalent (univariate analysis) in the group of patients with events. Logistic multivariate analysis showed that ApoE polymorphism (P =. 004, odds ratio [OR] 6.8, 95% confidence interval [CI] 2 to 22), family history (P =.005, OR 8.3, 95% CI 2 to 35), smoking after acute myocardial infarction (P =.008, OR 10.9, 95% CI 2 to 62), and left anterior descending coronary artery disease (P =.02. OR 6.6, 95% CI 1.3 to 33) were independent predictors of adverse events.

CONCLUSIONS

Myocardial infarction at a young age is commonly characterized by evidence of multiple cardiovascular risk factors and by a favorable prognosis in short- and medium-term follow-up. Evidence of significant disease at coronary angiography suggests the presence of a premature atherosclerotic process. ApoE polymorphism (presence of epsilon4 allele) appears to be a strong independent predictor of adverse events, suggesting a remarkable influence in the accelerated coronary disease.

Plasma activity and insertion/deletion polymorphism of angiotensin I-converting enzyme: a major risk factor and a marker of risk for coronary stent restenosis

BACKGROUND

Tissue proliferation is almost invariably observed in recurrent lesions within stents, and ACE, a factor of smooth muscle cell proliferation, may play an important role. Plasma ACE level is largely controlled by the insertion/deletion (I/D) polymorphism of the enzyme gene. The association among restenosis within coronary stents, plasma ACE level, and the I/D polymorphism is analyzed in the present prospective study.

METHODS AND RESULTS

One hundred seventy-six consecutive patients with successful, high-pressure, elective stenting of de novo lesions in the native coronary vessels were considered. At follow-up angiography, recurrence was observed in 35 patients (19.9%). Baseline clinical and demographic variables, plasma glucose and serum fibrinogen levels, lipid profile, descriptive and quantitative angiographic data, and procedural variables were not significantly different in patients with and without restenosis; mean plasma ACE levels (+/-SEM) were 40.8+/-3.5 and 20.7+/-1.0 U/L, respectively (P<.0001). Diameter stenosis percentage and minimum luminal diameter at 6 months showed statistically significant correlation with plasma ACE level (r=.352 and -.387, respectively P<.001). Twenty-one of 62 patients (33.9%) with D/D genotype, 13 of 80 (16.3%) with I/D genotype, and 1 of 34 (2.9%) with I/I genotype showed recurrence; the restenosis rate for each genotype is consistent with a codominant expression of the allele D.

CONCLUSIONS

In a selected cohort of patients, both the D/D genotype of the ACE gene, and high plasma activity of the enzyme are significantly associated with in-stent restenosis. Continued study with clinically different subsets of patients and various stent designs is warranted.

Seventy-five nuclear DNA polymorphisms in an Italian sample: a comparative worldwide study

A well defined Italian sample from Trino Vercellese (Northern Italy) is analysed for 75 nuclear DNA RFLPs. It represents the only European sample [Matullo et al 1994] which is unmixed in a comparative study of eight populations from four continents [Bowcock et al 1991a; Lin et al 1994]. Genetic substructure of this sample has been investigated by allele sharing distances and no bias or higher homogeneity is shown. Genetic variability between populations was measured by the FST statistics (average FST was 0.138 +/- 0.086). Average heterozygosity for eight populations was 0.312 +/- 0.069. Genetic distances were evaluated between pairs of populations. Phylogenetic trees were reconstructed and principal component analysis performed. Particular attention has been given to the genetic relationship between our sample and the mixed-Caucasoid sample: 14 out of 75 markers show statistically significant frequency differences (P < 0.05), 5 of which are significant at a probability level < 1%: GH/Bg1II (Lower system), D7S1/HindIII, D17S71/MspI, EPB3/PstI, HLA-DQA. Hypotheses on admixed origin of Europeans has been discussed.

Restriction of the T-cell receptor V delta gene repertoire is due to preferential rearrangement and is independent of antigen selection

To determine whether the limited V gene usage by the T-cell receptor delta (TCRD) chain is dictated by preferential rearrangement or by antigen selection, we characterized and compared the TCRDV gene repertoire of the productive with that of the unproductive allele in 80 human TCRG/TCRD clones. Six different V genes were found on the expressed allele; two of them, provisionally named DV7 and DV8, have not been described before on the surface of TCRG/TCRD T cells. Overall, six V genes and six non-V elements were isolated from the unproductive allele. Interestingly, the same set of genes was rearranged both in the productive and in the unproductive chromosome. These findings seem to suggest that antigen-independent mechanisms play a major role in the restriction of the TCRDV gene repertoire.

Analysis of HLA-A, C, B, DR and DQ loci in an Italian sample of possible Celtic origin

Trino Vercellese, a village of Piedmont (Italy), was selected with the aim at reconstructing the genetic history of a putative Celtic sample known to be settled in Italy with the name of Rigomagus since pre-roman times. The HLA-A, Cw, B, DR and DQ antigens of 101 unrelated individuals have been typed. The antigens characterizing this sample for their higher frequency are shown to be A3, A11, A32, B35, B39, Bw52, Cw4, DRw11, DRw13, DQw7. Gene frequencies are estimated by maximum likelihood and Hardy-Weinberg equilibrium was tested with no deviant genetic locus. Two-locus haplotype frequencies were also estimated and those with significant associations tabulated. "Extended" haplotypes were reconstructed: the three most frequent haplotypes (covering a total frequency of 11.5%) share the same Cw, B, DR and DQ alleles. Comparisons with other Italian and European samples are indicated to challenge archeological evidence of a pre-roman genetic stratification of the people living in our old Rigomagus.

T cell receptor V delta 2-C alpha transcripts are present in the thymus but virtually absent in the periphery

To investigate whether the V delta 2-(D)-J alpha gene configuration, characteristically associated with the major subset of acute lymphoblastic leukemias in humans, might have a physiologic role in T cell ontogeny, we have looked for V delta 2-C alpha transcripts in the thymus and peripheral blood of normal donors. Here we show by PCR analysis that these transcripts are virtually absent in the PBMC, whereas they are present in fetal and postnatal thymus. Interestingly, over 80% of 43 V delta 2-C alpha cDNAs randomly isolated from one postnatal thymus appeared to maintain an open reading frame. This suggests that in the thymus the V delta 2-C alpha products might be exposed to selective pressure. Furthermore, in two of three thymuses tested for J alpha usage, it was found overrepresented in a J alpha element (J alpha 58) located 2 kb downstream to a pseudo-J (J alpha 61), known to be a hot spot of recombination in alpha beta committed cells. A possible alternative pathway to alpha beta T cell differentiation via a V delta 2-J alpha intermediate is discussed.

T cell receptor V delta 2-C alpha transcripts are present in the thymus but virtually absent in the periphery

To investigate whether the V delta 2-(D)-J alpha gene configuration, characteristically associated with the major subset of acute lymphoblastic leukemias in humans, might have a physiologic role in T cell ontogeny, we have looked for V delta 2-C alpha transcripts in the thymus and peripheral blood of normal donors. Here we show by PCR analysis that these transcripts are virtually absent in the PBMC, whereas they are present in fetal and postnatal thymus. Interestingly, over 80% of 43 V delta 2-C alpha cDNAs randomly isolated from one postnatal thymus appeared to maintain an open reading frame. This suggests that in the thymus the V delta 2-C alpha products might be exposed to selective pressure. Furthermore, in two of three thymuses tested for J alpha usage, it was found overrepresented in a J alpha element (J alpha 58) located 2 kb downstream to a pseudo-J (J alpha 61), known to be a hot spot of recombination in alpha beta committed cells. A possible alternative pathway to alpha beta T cell differentiation via a V delta 2-J alpha intermediate is discussed.

RFLP analysis on a sample from northern Italy

We analysed a sample of 55 unrelated individuals from Trino Vercellese, a village in northern Italy. It represents the only European sample which is unmixed in a comparative study of eight populations from four continents [Bowcock et al 1991a; Lin et al 1994]. RFLP analysis was performed on 32 DNA markers, for a total of 37 independent alleles. Genetic variability between populations was measured by the FST statistics (average FST is 0.138). Average heterozygosity was calculated for each marker and for each population. Genetic distances were evaluated between pairs of populations. Phylogenetic trees were reconstructed and principal component analysis performed.

High prevalence of T-cell receptor V delta 2-(D)-D delta 3 or D delta 1/2-D delta 3 rearrangements in B-precursor acute lymphoblastic leukemias

Rearrangement of the immunoglobulin (Ig) and T-cell receptor (TcR) genes generally has been considered a useful marker of B- and T-cell lineage in lymphoproliferative disorders. However, concomitant rearrangements of Ig and TcR genes have been commonly reported in the most immature lymphoid malignancies, mainly in B-cell precursor acute lymphoblastic leukemia (ALL). To better characterize the nature of this lineage promiscuity, we have analyzed the configuration of the TcR delta locus in 75 B-precursor ALL. The large majority of cases (87%) displayed a rearrangement or deletion at the delta locus. Among the 57 nondeletional rearrangements, two patterns were predominant and both appeared to derive from partial joining: a V delta-(D)-D delta 3 (32/57) and a D delta 1/2-D delta 3 (11/57) type. A single V delta gene (V delta 2) appeared to be involved in the first type of rearrangement. These findings are at variance with T-ALL, where rearrangements 5' to V delta 2 are usually found. It remains to be elucidated whether this incomplete attempt of V delta 2 gene assembly is related to the neoplastic event or represents a physiologic predisposition occurring during early stages of the normal lymphocyte differentiation.