An evaluation of tumor necrosis factor microsatellite alleles in genetic susceptibility to multiple sclerosis

We have analyzed the distribution of tumor necrosis factor (TNF) a and -b microsatellite alleles in HLA-DQ and -DR typed Swedish patients with multiple sclerosis (MS) (n = 122) and ethnically matched control subjects (n = 178). We found significant differences in the frequencies of TNFa and TNFb alleles between patients and controls. TNFaII was significantly associated with MS. This was also the case for the combination of TNFaII with TNFb4. However, TNFaII (alone or in combination with TNFb4) did not show any disease association independent of DQA1*0102/ DQB1*0602/DR2, whereas the previously reported strong association with HLA-DQA1*0102/DQB1*0602/DR2 in Scandinavian populations was confirmed. Therefore the association of TNFaII (and TNFb4) is most likely secondary to the increase of DQA1*0102/DQB1*0602/DR2 in MS patients. The proportion of TNFa6 positive individuals was lower among DR2-negative MS patients than among DR2-negative controls (P = 0.08). Since the presence of the TNFa6 allele correlates with low TNF alpha production in response to lipopolysaccharide, it could be speculated that DR2-negative MS patients have an increased risk of being high TNF alpha producers in response to exogenous stimuli.     

Ancient conservation of trinucleotide microsatellite loci in polistine wasps

Several recent pieces of clinical evidence have demonstrated that reduction of cholesterol levels positively affects outcomes in both primary and secondary prevention of atherosclerotic vascular disease. The mechanism for the beneficial effects of cholesterol-lowering interventions has been attributed to decreased progression or actual regression of plaques as a consequence of reduced circulating LDL concentrations. Other mechanisms can be hypothesized, including a "stabilizing" effect on plaques, which would decrease chances of rupture, and an improvement of endothelial dysfunction, which would slow-down the progression of the disease. This review is aimed at offering an update on such mechanisms. The hypothesis of a direct action of cholesterol-lowering agents, in particular of statins, on endothelial functions, independently of LDL-lowering effects, will be discussed.     

Detection of loss of heterozygosityat microsatellite loci in esophageal squamous-cell carcinoma

Microsatellite alterations at 3 genetic loci (chromosomes 2p, 3p and 17p) were analyzed in 25 tumors (20 primary tumors and 5 metastatic lymph nodes) from 20 patients after surgical treatment for esophageal cancer. DNA samples from tumors were compared with control DNA from lymphocytes obtained from the peripheral blood of the individual patients. Microsatellite alterations [microsatellite instability (MSI) and loss of heterozygosity (LOH)] were detected in 15% of 20 primary tumors with marker D2S123 (chromosome 2p), 55% with marker D3S1067 (chromosome 3p) and 50% with marker TP53 (chromosome 17p). The 3-year disease-free survival rate of the 10 patients who had tumors without alterations or with an alteration at only 1 of 3 microsatellite loci was 75% and it was better than that of the 10 patients who had tumors with alterations at 2 or 3 microsatellite loci (48%, p = 0.049). This finding suggests that esophageal cancer with alterations at multiple microsatellite loci might have strong malignant potential. However, MSI was only detected in one of 20 patients, which suggests that MSI might not play an important role in the development of this cancer. Three of 5 metastatic lymph nodes showed no LOH even though primary tumors of these patients exhibited LOH with 1 or 2 markers, and 1 metastatic lymph node had LOH that was detected with D3S1067 even though the primary tumor of this patient had no LOH with all markers. Thus, clonal heterogeneity might exist in esophageal squamous-cell carcinomas.     

Detection of putative loci affecting conformational type traits in an elite population of United States Holsteins using microsatellite markers

Quantitative trait loci affecting conformational type traits were studied in seven large grandsire families of US Holsteins using the granddaughter design and 16 microsatellite markers on 10 chromosomes. The most significant marker effect was marker BM203 (chromosome 27) for dairy form in a single grandsire family. A multivariate analysis for dairy form and milk yield was also conducted, and the result was highly significant, indicating that a segregating quantitative trait locus or loci affecting dairy form and milk yield could exist near BM203 on chromosome 27. Marker BM1258 (chromosome 23) had a significant effect on udder depth. A multivariate analysis on udder depth and somatic cell score was conducted for markers 513 and BM1258, and both markers showed significant effects on these two traits, indicating that one or several quantitative trait loci affecting udder depth and mastitis might exist on chromosome 23. Marker BM4204 (chromosome 9) had a significant effect on foot angle and on the composite index of traits pertaining to feet and legs, indicating that one or several quantitative trait loci affecting traits pertaining to feet and legs might exist on chromosome 9. Selection on these markers could increase genetic progress within these families.     

Differential structuring of human populations for homologous X and Y microsatellite loci

The global pattern of variation at the homologous microsatellite loci DYS413 (Yq11) and DXS8174 and DXS8175 (Xp22) was analyzed by examination of 30 world populations from four continents, accounting for more than 1,100 chromosomes per locus. The data showed discordant patterns of among- and within-population gene diversity for the Y-linked and the X-linked microsatellites. For the Y-linked polymorphism, all groups of populations displayed high FST values (the correlation between random haplotypes within subpopulations, relative to haplotypes of the total population) and showed a general trend for the haplotypes to cluster in a population-specific way. This was especially true for sub-Saharan African populations. The data also indicated that a large fraction of the variation among populations was due to the accumulation of new variants associated with the radiation process. Europeans exhibited the highest level of within-population haplotype diversity, whereas sub-Saharan Africans showed the lowest. In contrast, data for the two X-linked polymorphisms were concordant in showing lower FST values, as compared with those for DYS413, but higher within-population variances, for African versus non-African populations. Whereas the results for the X-linked loci agreed with a model of greater antiquity for the African populations, those for DYS413 showed a confounding pattern that is apparently at odds with such a model. Possible factors involved in this differential structuring for homologous X and Y microsatellite polymorphisms are discussed.     

Allelic imbalance and instability of microsatellite loci on chromosome 1p in human non-small-cell lung cancer

The mapping of allelic loss on the short arm of chromosome 1 has been performed in non-small-cell lung cancer. We used a set of 11 microsatellite loci spanning 1p to examine the frequency of allelic imbalance in a panel of 58 tumours. Fifty-one of 58 (87.9%) cases have shown somatic allelic loss at one or more loci tested. The two shortest regions of the overlap (SRO) of the deletions have been identified: SRO 1 at 1p13.1 and SRO 2 at 1p32-pter. Allelic losses at these regions have been compared among adenocarcinoma and squamous cell carcinoma and no difference has been found. In contrast to SRO 1, deletions at SRO 2 significantly correlated with advanced stage of the disease as well as post-operative metastasizing and relapse. These data may suggest that SRO 1 and SRO 2 can harbour tumour-supressor genes (TSGs) involved in different stages of NSCLC development. SRO 2 is still quite large and its refined mapping should help attempts to clone and identify the putative TSG(s). Microsatellite instability (replication errors) affecting only 6 (10.3%) of 58 tumour samples is an infrequent genetic alteration at the loci tested.     

Multiple levels of single-strand slippage at cetacean tri- and tetranucleotide repeat microsatellite loci

Between three and six tri- and tetranucleotide repeat microsatellite loci were analyzed in 3720 samples collected from four different species of baleen whales. Ten of the 18 species/locus combinations had imperfect allele arrays, i.e., some alleles differed in length by other than simple integer multiples of the basic repeat length. The estimate of the average number of alleles and heterozygosity was higher at loci with imperfect allele arrays relative to those with perfect allele arrays. Nucleotide sequences of 23 different alleles at one tetranucleotide repeat microsatellite locus in fin whales, Balaenoptera physalus, and humpback whales, Megaptera novaeangliae, revealed sequence changes including perfect repeats only, multiple repeats, and partial repeats. The relative rate of the latter two categories of mutation was estimated at 0.024 of the mutation rate involving perfect repeats only. It is hypothesized that single-strand slippage of partial repeats may provide a mechanism for counteracting the continuous expansion of microsatellite loci, which is the logical consequence of recent reports demonstrating directional mutations. Partial-repeat mutations introduce imperfections in the repeat array, which subsequently could reduce the rate of single-strand slippage. Limited computer simulations confirmed this predicted effect of partial-repeat mutations.     

Partial rescue of the prophase I defects of Atm-deficient mice by p53 and p21 null alleles

Patients with the human disorder ataxia-telangiectasia (A-T; refs 1,2) and Atm-deficient mice have a pleiotropic phenotype that includes infertility. Here we demonstrate that male gametogenesis is severely disrupted in Atm-deficient mice in the earliest stages of meiotic prophase I, resulting in apoptotic degeneration. Atm is required for proper assembly of Rad51 onto the chromosomal axial elements during meiosis. In addition, p53, p21 and Bax are elevated in testes from Atm-deficient mice. To determine whether these elevated protein levels are important factors in the meiotic disruption of Atm-deficient mice, we analysed the meiotic phenotype of Atm/p53 or Atm/p21 double mutants. In these double mutants, meiosis progressed to later stages but was only partly rescued. Assembly of Rad51 foci on axial elements remained defective, and gametogenesis proceeded only to pachytene of prophase I. Previous results demonstrated that mice homozygous for a null mutation in Rad51 (ref. 6) display an early embryonic lethal phenotype that can be partly rescued by removing p53 and/or p21. Because Atm-deficient mice are viable but completely infertile, our studies suggest that the Rad51 assembly defects and elevated levels of p53, p21 and Bax represent tissue-specific responses to the absence of Atm.     

Clinicopathological significance of altered loci of replication error and microsatellite instability-associated mutations in gastric cancer

Replication errors (RERs) judged by microsatellite instability and its associated mutations have been recognized as an important mechanism in tumorigenesis of gastric cancers (GCs). To gain a deeper insight into its significance, we examined the frequency of RERs using nine microsatellite markers and screened mutations in the polydeoxyadenine tract of the transforming growth factor beta type II receptor gene (TGF-betaRII) and polydeoxyguanine tracts of insulin-like growth factor II receptor and BAX genes. Twenty-four (30%) of 80 patients with GC had RERs, of which 3, 8, and 13 had one, two, and three or more loci, respectively. In 13 tumors with RERs in three or more loci, frameshift mutations of TGF-betaRII, insulin-like growth factor II receptor, and BAX were identified in 12, 3, and 2, respectively. Compared with GC with none, one or two RER-positive loci as a group, GC with RERs in three or more loci showed a significantly higher frequency of antral location (12 of 13 versus 35 of 67; P = 0.01), intestinal subtype (11 of 13 versus 30 of 67; P = 0.01), and previous Helicobacter pylori infection (12 of 13 versus 41 of 67; P = 0.05) and a lower incidence of lymph node metastasis (5 of 13 versus 49 of 67; P = 0.02) and tended to be in an advanced stage (12 of 13 versus 54 of 67; P = 0.28). These data indicate that GC with multiple RERs manifest distinct clinicopathological characteristics, and that a high frequency of frameshift mutations involving the TGF-betaRII gene may be causatively linked with tumorigenesis and progression.     

Characterization of microsatellite loci in a pelagic spawner: the bluehead wrasse, Thalassoma bifasciatum

Securing informed consent, though vital to any defense, will not shield a practitioner from a malpractice claim. That is because courts generally hold that patients cannot consent to negligent treatment.     

Frequency of loci of HLA-DRB1* and -DQB1* alleles in the Slovak population]

Results on HLA-DRB1* and HLA-DQB1* allele frequencies in the Slovak population by PCR-SSP method are presented. HLA-DRB1* alleles were determined in 130 and HLA-DQB1* alleles in 143 healthy unrelated individuals. The highest frequency was observed for the alleles HLA-DRB1*1101-13 (0.203), HLA-DRB1*0701 (0.142), HLA-DQB1*0301 (0.244), and HLA-DQB1*0201 (0.209). The least frequent alleles were HLA-DRB1*1402-6-9, HLA-DRB1*0901 (both 0.0038), HLA-DQB1*0401 (0.007), and HLA-DQB1*0601 (0.0035). The results obtained by DNA-typing were compared with those calculated from the serological study. No statistically significant differencies were found. The allele frequencies obtained in our study were also compared with those of the Czech and Austrian populations. No statistically significant differencies were observed. (Fig. 2, Tab. 3, Ref. 13.)