Further data on the microsatellite locus D12S67 in worldwide populations: an unusual distribution of D12S67 alleles in Native Americans

We report the frequencies of alleles at the microsatellite locus D12S67 in 2 widely separated ethnic groups of the world: 2 populations from Sulawesi, an island in the Indonesian archipelago, and 5 Native American tribes of Colombia, South America. The allele frequencies in the Minihasans and Torajans of Sulawesi are similar to each other (but the modal class allele is different) and in general agreement with those reported in mainland Asian groups, but different from both Europeans and Chinese Han of Taiwan. The 5 Native American tribes (Arsario, Kogui, Ijka, Wayuu, and Coreguaje) display different allele frequencies from those seen in Sulawesi populations, in other groups from Europe and mainland Asia, and in Chinese Han of Taiwan. Native Americans exhibit a bimodal distribution of alleles, unlike other groups, with significant differences among the tribes. The Arsario and Kogui have no admixture with Europeans or Africans and are the most distinctive, while the Wayuu have the most admixture and show most similarity to other groups. The data suggest that nonadmixed Native Americans may be quite distinctive with respect to this marker. The most common allele varies across the 5 tribes, from 249 base pairs to 261 base pairs. All samples exhibit Hardy-Weinberg genotype proportions; heterozygosities are lowest in the 2 nonadmixed Native American tribes. Examination of all the available data indicates that some east Asian and southeast Asian groups are characterized by a high frequency of smaller sized D12S67 alleles, while other populations have a greater proportion of the larger sized alleles. The cumulative, though still highly restricted, population data on locus D12S67 demonstrate that it may be of considerable value in anthropological genetic studies of ethnic groups. Data are required on Native Americans outside Colombia before this marker can be used in admixture studies of this group.     

Expression of the tumor necrosis factor locus is not necessary for the cytolytic activity of T lymphocytes

In order to test whether tumor necrosis factors alpha (TNF-alpha) or beta (TNF-beta, also known as lymphotoxin) are involved in the lysis of target cells by cytolytic T lymphocytes, we probed for the presence of the TNF mRNAs in several quiescent and activated CTL clones. No TNF mRNA could be found in constitutively cytolytic Lyt-2+ clones, and only two out of three clones tested accumulated TNF mRNA after stimulation with phorbol myristate acetate and ionomycin. Of two L3T4+ clones that can be induced to become cytolytic by a combination of antigen and IL-1, only one accumulated TNF-beta mRNA in the process. The PC60 rat X mouse T cell hybrid, which becomes cytolytic in response to a combination of IL-1 and IL-2, also failed to accumulate TNF mRNA after stimulation with these agents. Our results strongly suggest that TNF-alpha or -beta are not necessary agents of the cytolytic activity exhibited by antigen-specific T lymphocytes.     

Aspartic acid 50 and tyrosine 108 are essential for receptor binding and cytotoxic activity of tumour necrosis factor beta (lymphotoxin).

Single amino acid substitutions were generated in predicted hydrophilic loop regions of the human tumour necrosis factor beta (TNF-beta) molecule, and the mutant proteins were expressed in Escherichia coli and purified. Mutants with single amino acid changes at either of two distinct loop regions, at positions aspartic acid 50 or tyrosine 108, were found to have greatly reduced receptor binding and cytotoxic activity. These two regions in TNF-beta correspond to known loop regions where mutations also result in loss of biological activity of TNF-alpha, a related cytokine which shares the same cellular receptors with TNF-beta. The two distinct loops at positions 31-34 and 84-89 in the known three-dimensional structure of TNF-alpha (equivalent to positions 46-50 and 105-110 respectively in TNF-beta), lie on opposite sides of the TNF-alpha monomer. When the TNF-alpha monomer forms a trimer, the two loops, each from a different subunit of the trimer, come together and lie in a cleft between adjacent subunits. Together, these findings suggest that a TNF receptor binds to a cleft between subunits via surface loops at amino acid residues 31-34 and 84-89 in TNF-alpha, and similarly via surface loops including amino acids aspartic acid 50 and tyrosine 108 in TNF-beta.     

中国甘肃裕固族X-STR遗传多态性及其应用研究

为研究中国甘肃裕固族人群X染色体STR基因座的遗传多态性及其在群体遗传学中的应用, 采用PCR扩增, 变性聚丙烯酰胺凝胶电泳结合银染显带技术, 检测120名(女55, 男65)裕固族无关个体9个X-STR基因座(DXS7130、DXS7132、DXS6804、DXS7423、DXS7424、DXS6789、DXS6799、DXS8378和HPRTB)的等位基因频率及基因型分布, 以及存在连锁的X-STR基因座的单体型多态性; 同时, 利用X-STR构建系统发生树和进行聚类分析, 分析裕固族与我国其他民族的群体遗传关系。结果发现, DXS7130、DXS7132、DXS6804、DXS7423、DXS7424、DXS6789、DXS6799、DXS8378和HPRTB基因座分别检出8、6、6、5、6、7、6、4、6个等位基因和16、14、13、6、13、20、11、6、12种基因型, 9个X-STR基因座女性的基因型频率分布均符合Hardy-Weinberg平衡(P>0.05)。由DXS7130和DXS8378基因座组成的单体型共检出15种, 由DXS6789、DXS6799、DXS7424和DXS6804基因座组成的单体型共检出55种, 单体型多样性分别为0.8212和0.9947。群体遗传多态性指标显示上述9个X-STR基因座均具有较高多态性, 在法医学个体识别、亲权鉴定及群体遗传学研究中有重要应用价值。对裕固族与我国其他民族群体遗传关系的研究结果显示, 裕固族与蒙古族及同处西北的汉族、藏族关系较近, 而与回族、维族关系较远, 提示裕固族是一个在起源上与蒙古族、汉族以及藏族关系密切的民族群体。     

Phylogeography and recent emergence of the Old World screwworm fly, Chrysomya bezziana, based on mitochondrial and nuclear gene sequences

Abstract.  A previous study had identified an African and an Asian race of the Old World screwworm fly, Chrysomya bezziana Villeneuve (Diptera: Calliphoridae), based on the 3' terminal 279 basepairs (bp) of the mitochondrial cytochrome b gene. The current study improved the phylogeographic resolution of cytochrome b for this species by characterizing more of the gene (the 3' terminal 715 bp) and by sampling more geographical populations, including Oman, Iran, Hong Kong and the Indonesian islands of Sulawesi and East Sumba. Strong support was found for recognizing an African race, but not for a monophyletic Asian race. The cladistic and genealogical relationships among the Asian populations were complex. There was sufficient genetic homogeneity throughout separate regions (mainland Asia and each Indonesian island) to suggest that there are no reproductive barriers within each region that might necessitate the production of more than one strain for control by the sterile insect technique (SIT). Primers were designed for the amplification by polymerase chain reaction of two nuclear loci, the highly conserved elongation factor-1α gene and the less conserved white gene, and the preliminary results indicated that these genes showed the same pattern of small-scale regional variation as cytochrome b . The cytochrome b haplotypes are useful markers for identifying the geographical origins of any emerging infestations of the species: the absence of Indonesian and African haplotypes in the Middle East demonstrates that the large-scale transport of livestock is not spreading Old World screwworm.     

Tumor necrosis factors alpha and beta differ in their capacities to generate interleukin 1 release from human endothelial cells

The capacity of the tumor necrosis factors, TNF-alpha and TNF-beta, products of activated macrophages and lymphocytes, respectively, to stimulate interleukin 1 (IL-1) release from endothelial cells derived from human umbilical veins was examined in vitro. Recombinant TNF-alpha caused IL-1 release by 4 hr with maximal levels of 17 U/ml by 24 hr; half-maximal stimulation occurred at approximately 80 pM. In contrast, recombinant TNF-beta was a relatively poor stimulus for IL-1 release. Even at concentrations as high as 600 pM, only 3 U of IL-1/ml were recovered; maximal IL-1 release (10 to 12 U/ml) required up to 5 nM TNF-beta. Natural, glycosated human TNF-beta was comparable in activity to recombinant TNF-beta. TNF-beta did not directly inhibit the IL-1 comitogenesis assay, nor was there evidence that TNF-beta induced the release of an IL-1 inhibitor, in that supernatants generated in the presence of TNF-beta did not inhibit thymocyte proliferation to a recombinant IL-1 standard. Binding of the recombinant TNF to endothelial monolayers was assessed by using [125I]TNF-alpha in competition studies with cold TNF-alpha and TNF-beta. Binding of TNF-alpha was half-maximal at 80 pM with an average of 664 receptors/cell and Kd = 0.043 nM. Although TNF-beta was capable of fully competing for [125I]TNF-alpha binding, half-maximal binding occurred at 800 pM TNF-beta. These data suggest that the TNF receptors on human endothelial cells may reflect the structural differences between these two homologous cytokines.     

Production of TNF-alpha and TNF-beta by staphylococcal enterotoxin A activated human T cells

Staphylococcal enterotoxin at concentrations of less than 1 pg/ml induces significant TNF activity in human peripheral blood T cells and monocytes. Maximal TNF activity is routinely detected after 48 to 72 h of culture. IL-2 and IL-4 were both growth promoting for human T cells but only IL-2 could efficiently induce TNF production. The production of TNF-alpha and TNF-beta differed greatly in kinetics. An early intracytoplasmatic production of TNF-alpha after 6 h was detected in both monocytes and T cells whereas a late production of TNF-beta (lymphotoxin) after 48 h, occurred in the T cell population. Induction of TNF-alpha and TNF-beta production by Staphylococcal enterotoxin requires the presence of both monocytes and T cells. The CD4+45R- but not CD4+45R+ and CD8+ cells supported TNF-alpha production in monocytes. The main lytic component from Staphylococcal enterotoxin-activated mononuclear cells is TNF-beta. CD4+ and CD8+ T cells produced about equal amounts of biologically active TNF into the culture supernatants but a fourfold higher frequency of TNF-beta producing cells was demonstrated among CD4+ vs CD8+ cells. The CD4+45R- T cell subset was an efficient producer of TNF-beta and IFN-gamma whereas the CD4+45R+ T cell subset produced significant amounts of TNF-beta but only marginal amounts of IFN-gamma.     

贵州四个民族人群线粒体DNA编码区的多态性

目的研究贵州土家族、侗族、仡佬族和彝族人群线粒体DNA（mtDNA）编码区的核苷酸多态性。方法采用PCR-RFLP技术和DNA测序法对贵州4个群体145例样本mtDNA编码区的8个SNP基因座及COⅡ/tRNAlys基因间9 bp缺失进行多态性分析。结果贵州4个民族群体的9 bp缺失频率依次为土家族18.4%,侗族29.7%,仡佬族25%,彝族16.7%,平均缺失频率为22.8%;在8个SNP基因座中,A10398G、C10400T突变在4个群体中较普遍;A663G、C5178A和G12406A突变在部分民族群体中也有较高的频率;共检测出14种单倍型,其中仡佬族11种,土家族10种,侗族8种,彝族6种。结论贵州4个民族群体mtDNA编码区可能存在不同的突变热点,在等位基因和单倍型分布频率上存在一定差异。     

Tumor necrosis factors alpha and beta induce osteoblastic cells to stimulate osteoclastic bone resorption

Antigen- or mitogen-stimulated leukocytes release bone-resorbing activity into culture supernatants in vitro. Among the agents likely to be present in such supernatants are monocyte-derived tumor necrosis factor (TNF-alpha) and lymphocyte-derived tumor necrosis factor (TNF-beta) (lymphotoxin), both of which have recently been shown to stimulate bone resorption in organ culture. To identify the mechanism of action of these agents, we compared bone resorption by isolated osteoclasts with bone resorption by osteoclasts cocultured with osteoblastic cells, and with bone resorption by osteoclasts incubated with supernatants from osteoblastic cells, in the presence and absence of recombinant TNF-alpha and TNF-beta. We found that neither TNF-alpha nor TNF-beta had any significant effect on bone resorption by isolated osteoclasts, but in the presence of osteoblasts the agents caused a twofold to threefold stimulation of bone resorption. A similar degree of stimulation was achieved by supernatants from osteoblasts incubated with TNF before addition to osteoclasts, compared with supernatants to which TNF were added after osteoblast incubation. These experiments suggest that TNF-alpha and TNF-beta stimulate bone resorption through a primary effect on osteoblastic cells, which are induced by TNF to produce a factor that stimulates osteoclastic resorption. Half-maximal stimulation of resorption occurred at 1.5 X 10(-10) M and 2.5 X 10(-10) M for TNF-alpha and TNF-beta, respectively. This degree of potency is comparable to that of parathyroid hormone, the major physiologic systemic regulator of bone resorption, and suggests that the TNF may exert a significant influence on osteoclastic bone resorption in vivo.     

Linked vs unlinked markers: multilocus microsatellite haplotype-sharing as a tool to estimate gene flow and introgression

We have explored the use of multilocus microsatellite haplotypes to study introgression from cultivated (Malus domestica) into wild apple (Malus sylvestris), and to study gene flow among remnant populations of M. sylvestris. A haplotype consisted of alleles at microsatellite loci along one chromosome. As destruction of haplotypes through recombination occurs much faster than loss of alleles due to genetic drift, the lifespan of a multilocus haplotype is much shorter than that of the underlying alleles. When different populations share the same haplotype, this may indicate recent gene flow between populations. Similarly, haplotypes shared between two species would be a strong signal for introgression. As the expected lifespan of a haplotype depends on the strength of the linkage, the length [in centiMorgans (cM)] of the haplotype shared contains information on the number of generations passed. This application of shared haplotypes is distinct from using haplotype-sharing to detect association between markers and a certain trait. We inferred haplotypes for four to eight microsatellite loci on Linkage Group 10 of apple from genotype data using the program phase, and then identified those haplotypes shared between populations and species. Compared with a Bayesian analysis of unlinked microsatellite loci using the program structure, haplotype-sharing detected a partially different set of putative hybrids. Cultivated haplotypes present in M. sylvestris were short (< 1.5 cM), indicating that introgression had taken place many generations ago, except for two Belgian plants that contained a haplotype of 47.1 cM, indicating recent introgression. In the estimation of gene flow, F(ST) based on unlinked loci indicated small (0.032-0.058) but statistically significant differentiation between some populations only. However, various M. sylvestris haplotypes were shared in nearly all pairwise comparisons of populations, and their length indicated recent gene flow. Hence, all Dutch populations should be considered as one conservation unit. The added value of using sharing of multilocus microsatellite haplotypes as a source of population genetic information is discussed.     

Genetic variability at the human tumor necrosis factor loci.

Variability in the structure of the human tumor necrosis factor (TNF-alpha) or lymphotoxin (TNF-beta) genes may contribute to the functional polymorphism of the HLA gene complex. We have characterized an allelic restriction fragment length polymorphism (RFLP) of the TNF-beta gene by using the restriction endonuclease NcoI. Digestion of genomic DNA with NcoI and Southern blotting by using TNF-alpha gene probes show 5.4-kb and 10.5-kb hybridizing fragments. In Caucasian populations, the 10.5-kb fragment is present in 64 to 72% of haplotypes. The polymorphic NcoI site is located within the first intron of the TNF-beta gene. Additional restriction fragment variability was demonstrated by digestion with AccI; however, this restriction fragment variability was not allelic in nature. Rather, it was a consequence of variable DNA methylation at AccI sites within and upstream of the TNF-beta gene. In peripheral blood leukocytes, methylation of the TNF-beta AccI sites was greatest in neutrophils (TNF-beta nonproducers), and lowest in T lymphocytes (the major producers of TNF-beta). These results suggest strongly that variation in DNA methylation may play an important role in regulation of the expression of the TNF-beta gene.     

Expression and regulation of tumor necrosis factor (TNF) and TNF-receptor family members in the macaque corpus luteum during the menstrual cycle

Members of the tumor necrosis factor (TNF)-receptor (R) family may be involved in the tissue remodeling that occurs in the primate corpus luteum (CL) during development and regression. As a first step towards addressing this issue, studies assessed TNF ligand-R expression and regulation in CL collected from monkeys during the early (ECL, Days 3-5), mid (MCL, Days 7-8), mid-late (MLCL, Days 10-11), late (LCL, Days 14-16), and very late (VLCL, menses) luteal phase of the menstrual cycle. CL were also collected after gonadotropin and/or steroid ablation and replacement (with hLH and the progestin R5020) for 3 days at mid-late luteal phase. TNF-alpha, -beta, FAS ligand (FASL), and TNF-R1 mRNA levels were two- to sixfold greater (P < 0.05) at the MLCL or LCL phase as compared to earlier (ECL, MCL). In contrast, TNF-R2 and FAS mRNA levels did not change during the luteal phase. Immunohistochemical staining for TNF-beta, TNF-R1, TNF-R2, FAS, and FASL was observed in luteal cells, whereas only TNF-beta staining was observed in endothelial cells. Several TNF-R components were influenced by LH and/or steroid ablation; notably, steroid ablation reduced (P < 0.05) luteal TNF-alpha, but not TNF-beta, mRNA levels, which was prevented by progestin treatment. In contrast, steroid ablation increased (P < 0.05) luteal cell immunostaining for FAS and FASL, which was reduced by progestin treatment. Thus, several members of the TNF R-ligand family are expressed in the primate CL in an LH- and/or progestin-dependent manner. Peak expression in the late luteal phase may signify a role for the TNF-R system in death receptor-mediated apoptosis during luteolysis.     

Minimal sharing of Y-chromosome STR haplotypes among five endogamous population groups from western and southwestern India

We attempt to address the issue of genetic variation and the pattern of male gene flow among and between five Indian population groups of two different geographic and linguistic affiliations using Y-chromosome markers. We studied 221 males at three Y-chromosome biallelic loci and 184 males for the five Y-chromosome STRs. We observed 111 Y-chromosome STR haplotypes. An analysis of molecular variance (AMOVA) based on Y-chromosome STRs showed that the variation observed between the population groups belonging to two major regions (western and southwestern India) was 0.17%, which was significantly lower than the level of genetic variance among the five populations (0.59%) considered as a single group. Combined haplotype analysis of the five STRs and the biallelic locus 92R7 revealed minimal sharing of haplotypes among these five ethnic groups, irrespective of the similar origin of the linguistic and geographic affiliations; this minimal sharing indicates restricted male gene flow. As a consequence, most of the haplotypes were population specific. Network analysis showed that the haplotypes, which were shared between the populations, seem to have originated from different mutational pathways at different loci. Biallelic markers showed that all five ethnic groups have a similar ancestral origin despite their geographic and linguistic diversity.     

Endotoxin and Staphylococcus aureus enterotoxin A induce different patterns of cytokines.

The effects of Staphylococcus aureus enterotoxin A (SEA) and lipopolysaccharide (LPS) in cytokine production were assessed at the single cell level in cells obtained from healthy blood donors. Cytokine production was studied with UV-microscopy of fixed and permeabilized cells stained with cytokine specific monoclonal antibodies. The cytokines evaluated included tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, IL-10, IL-2, IL-4, interferon (IFN)-gamma and TNF-beta. LPS exhibited marked production of IL-1 alpha, IL-1 beta, TNF-alpha, IL-6 and IL-8. After LPS stimulation IL-1 alpha, IL-1 beta, TNF-alpha and IL-8 were the dominating products, all peaking at or before 4 hours after cell stimulation. In addition, IL-10 production was evident after 12 hours of cell stimulation. The T-lymphocyte-derived cytokines TNF-beta, IL-2, IFN-gamma and IL-4 were never detected in the cultures. All cytokine production, except IL-8, was downregulated at 96 hours. In contrast, peak production of IL-1 alpha, IL-1 beta and IL-8, which were the dominant products, occurred after 12 hours in the SEA-stimulated cultures. Further, a significant T-lymphocyte production of TNF-beta, TNF-alpha, IFN-gamma and IL-2 was found with peak production 12-48 hours after initiation. Only low amounts of IL-6 were evident. The two types of cytokine pattern and kinetics found may correspond to the different clinical conditions after invasive Gram-negative Escherichia coli vs Gram-positive Staphylococcus aureus infections in humans, with a much more rapid onset of disease after E. coli infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differential priming for endotoxin-induced circulating cytokine production by tumor necrosis factor-alpha and interleukin 1 beta

In unprimed mice, a single injection of a non-lethal dose of lipopolysaccharide (LPS) produced a rise in tumor necrosis factor (TNF) and interleukin 6 (IL 6) activities. Peak serum concentrations were attained, respectively, 1.5 hr and 2.5 hr after the challenge. Pretreatment with recombinant human TNF-alpha (rHuTNF) had a priming effect for enhanced production of both serum cytokines without any change in kinetics. The enhancement was more pronounced in the TNF (15-fold) than in the IL 6 (4-fold) response. Recombinant murine TNF caused a comparable increase in LPS-induced cytokine release. In contrast, comparable pretreatment with another macrophage-derived cytokine, recombinant human interleukin 1 beta (HuIL1-beta), revealed a negative effect on LPS-induced TNF release whereas IL 6 in the blood reached levels similar to those found after priming with rTNF. Moreover, when administered in combination with rHuTNF, rHuIL1-beta inhibited the priming effect on TNF autocrine production.     

Inflammation, genetics, and ischemic heart disease: focus on the major histocompatibility complex (MHC) genes

BACKGROUND: Increasing data suggest that ischemic heart disease (IHD) shares several characteristics with common inflammatory diseases (such as rheumatoid arthritis), in which the pathogenetic role of inflammatory gene polymorphisms is well established. Variants in the genes for the major histocompatibility complex (MHC) molecules on the short arm of chromosome 6 show profound "linkage disequilibrium", leading to the formation of "haplotypes", i.e., frozen blocks of alleles travelling together through generations. DESIGN: We performed a review of published studies linking IHD with gene polymorphisms of the MHC molecules tumor necrosis factor (TNF)-alpha and -beta, the class II DR human leukocyte antigens, heat shock protein 70-1, hemochromatosis related gene, and complement C4. RESULTS: The emerging data are quite conflicting and do not provide definitive evidence for a role of these gene variants in the pathogenesis of IHD; a possible exception is the G252A and polymorphism in the TNF-beta gene (also known as lymphotoxin-alpha) which, in a comprehensive genome-scan linkage analysis of unrelated Japanese, but not in a smaller German population, was linked to myocardial infarction. However, some important biases appear, e.g. different study design and variable linkage disequilibrium among different populations. CONCLUSIONS: Preliminary positive results should encourage future studies to focus on clinical models of IHD with well-codified inflammatory components, using novel methods (such as haplotype analysis) to assess gene polymorphisms and their clinical effect.     

Genetic polymorphism analysis of 15 STR loci in Chinese Hui ethnic group residing in Qinghai province of China

In the present study, we investigated the diversity distributions of allelic frequencies of 15 short tandem repeats (STRs) loci in a sample of Chinese Hui ethnic group in the Ningxia Hui Autonomous Region. The allelic frequencies of the 15 STR loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA) were obtained from 2975 unrelated healthy Hui individuals. The STR genotyping data of all the samples were generated by DNA extraction, multiple amplification, GeneScan and genotype analysis. The genetic distances among different populations were calculated by using Nei's method and a phylogenetic tree was constructed based on the allelic frequencies of the same 15 STR loci using the neighbor-joining method. A total of 185 alleles were observed in the Hui population, with the corresponding allelic frequencies ranging from 0.0002 to 0.5322. Chi-Square tests showed that all STR loci were in Hardy-Weinberg equilibrium. The forensic statistical parameters of all the loci showed high values. The population data in this study were compared with the previously published population data from other ethnics or areas. The Hui population showed significant differences from the Minnan Han, Uigur, Ewenki, Yi, Tibetan, Maonan and Malay ethnic minority groups in some loci, and from the South Morocco population and the Moroccan population in all the loci. Our results are valuable for human individual identification and paternity testing in the Chinese Hui population and are expected to enrich the genetic information resources of Chinese populations.     

Microsatellite diversity and crossover regions within homozygous and heterozygous SLA haplotypes of different pig breeds

Our aim was to investigate microsatellite (MS) diversity and find crossover regions at 42 polymorphic MS loci in the swine leukocyte antigen (SLA) genomic region of 72 pigs with different well-defined homozygous and heterozygous SLA haplotypes. We analyzed the genetic polymorphisms of 42 MS markers in 23 SLA homozygous-heterozygous, common pig breeds with 12 SLA serological haplotypes and 49 National Institutes of Health (NIH) and Clawn homozygous-heterozygous miniature pigs with nine SLA serological or genotyped haplotypes including four recombinant haplotypes. In comparing the same and different haplotypes, both haplospecific patterns and allelic variations were observed at the MS loci. Some of the shared haplotype blocks extended over 2 Mb suggesting the existence of strong linkage disequilibrium (LD) in the entire SLA region. Crossover regions were easily defined by the MS markers within the class I and/or III region in the NIH and Clawn recombinant haplotypes. The present haplotype comparison shows that our set of MS markers provides a fast and cost-efficient alternative, or complementary, method to the serological or sequence-based determination of the SLA alleles for the characterization of SLA haplotypes and/or the crossover regions between different haplotypes.