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Intact chemoreceptor-based biosensors.

A receptrode biosensor is presented that uses intact chemoreceptor-based molecular recognition from antennular structures of the Hawaiian swimming crab species Portunis sanguinolentus. The sensor is coupled to a learning, pattern recognition calculation for performing analytical chemistry. Action potential waveforms are used to establish the identity of individual action potential types that can be associated to particular analytes. The pattern recognition calculations used are referred to as cluster analysis (CA) and principal component analysis (PCA). Action potential similarities are determined by using a dendrogram plot of the cluster analysis results and further elucidated by using principal component scores plots. Quantitative analysis was performed after classification of analyte and background responses. Chemoresponses to salinity and trimethylamine N-oxide, two chemical constituents that are found in the crustacean living environment, were investigated and gave analytic responses over several orders of magnitude.

Action Potentials↗

PubMed1992

Multivariate quantitative structure-toxicity relationships in a series of dopamine mimetics.

The techniques of principal components analysis and non-linear mapping are routinely used by computer chemists at SmithKline Beecham Pharmaceuticals in the process of drug development by relating the structure of a compound to its chemical activity. To our knowledge these techniques had not previously been applied to the association between the structure of a compound and its toxicological properties. Using a series of 12 structurally related compounds (11 were active dopamine mimetics and one was inactive), of which five were known to be teratogenic and seven were non-teratogenic, it was possible to demonstrate that molecular modelling techniques could be applied to differentiate toxicological data. The structure/property relationships of these compounds were investigated using calculated physicochemical properties, molecular modelling and multivariate statistical techniques. A data set of 56 molecular descriptors was used to represent this series of compounds. Analysis of the data set using principal components analysis and non-linear mapping suggested that teratogenicity was associated with four molecular properties. Moreover, the electronic nature of the 4-phenyl group appeared to be an important determinant of the teratogenesis.

Abnormalities, Drug-Induced↗

PubMed2026

Morphological characterization, genetic diversity and population structure of the rice blast pathogen Magnaporthe oryzae in Northeast India.

The blast pathogen, Magnaporthe oryzae, is one of the most destructive fungal pathogens of rice worldwide, yet its morphological features, genetic diversity and population structure in Northeast India remain poorly understood. In this study, twenty‒two M. oryzae isolates collected from eight states of Northeast India were characterized using morphological, molecular, and population genetic analyses. Morphological characterization revealed whitish to greyish‒white mycelia with sparse sporulation and colony diameters ranged from 36 to 90 mm, classifying the isolates into 14 fast and 8 slow‒growing groups. Whole genome sequencing was performed to enable both ITS‒based identification and SSR locus mining from the assembled genomes. Molecular identification using ITS rDNA sequences confirmed all isolates as M. oryzae, with 95.5-100% similarity. Phylogenetic analysis grouped the isolates into two major clades and identified seven ITS sequence types (GenBank Accessions: PX273287-PX273293). Genetic diversity assessed using 30 SSR markers revealed substantial polymorphism, with 1-7 alleles per locus and polymorphism information content (PIC) values ranging from 0.00 to 0.81. Heatmap clustering, dendrogram analysis, and distance metrics consistently identified two major genetic groups, with some isolates forming nearly identical clusters and others showing moderate divergence. Principal Component Analysis (PCA) and Principal Coordinates Analysis (PCoA) accounted for 87.8% of the total variance (PC1 and PC2 accounted for 54.4% and 33.4% respectively of the total variance) and revealed distinct outliers. Analysis of Molecular Variance (AMOVA) attributed 80% of the total genetic variation to differences among populations while only 20% was attributed to within population differences highlighting significant inter‒population divergence and clonal population structure. The study revealed substantial morphological and genetic diversity among M. oryzae populations in Northeast India, underscoring the need for region‒specific disease management strategies.

India↗

PubMed1979

Serum concentration of human alpha 2 HS glycoprotein during the inflammatory process: evidence that alpha 2 HS glycoprotein is a negative acute-phase reactant.

A nonspecific opsonin function has been ascribed to human alpha 2 HS glycoprotein. Its serum level has been shown to be decreased in trauma patients. Recent studies from this laboratory revealed a heterogeneity among the products obtained in the course of the preparation of the protein. To date, no definitive agreement existed with regard to a molecular homogeneous entity of alpha 2 HS glycoprotein (Ba-alpha 2 glycoproteins). The purpose of the current work was to study the variations in serum level of alpha 2 HS in patients suffering from an acute inflammatory process of bacterial etiology and to determine whether a decrease in alpha 2 HS was accompanied by the appearance of fragments of this protein in the serum. A method of preparing alpha 2 HS was thus developed, using an immune absorbent as a final purification step. In an intermediary step of the preparation, alpha 2 HS was found to bind zinc when metal chelate affinity chromatography was employed. Immunologically and physico-chemically pure alpha 2 HS was obtained. The protein consists of a unique polypeptide chain of about 50,000 daltons and has a unique amino-terminal residue, alanine. However, the protein maintained its molecular integrity with difficulty, and spontaneous fragments ranging from 30,000 to less than 10,000 daltons were produced in some of the preparations. No major modification in the molecular structure of the protein was noted in the sera of subjects suffering from an acute inflammatory process. Serum level of alpha 2 HS and alpha 1 antitrypsin (AT)was determined in 23 patients. When the acute-phase (AP-)reactant alpha 1 AT was increased (difference with normal mean greater than +2 or +3 SD), the sera showed a large decrease in alpha 2 HS (difference with normal mean less than -2 or -3 SD). The serum level of alpha 2 HS, albumin, alpha 2 macroglobulin, and of positive AP-reactants, orosomucoidinal study of seven patients. The results were submitted to a principal components analysis. Alpha 2 HS showed a negative correlation with the AP-reactants alpha 1 AT, orosomucoid, and haptoglobin (P less than 0.05) and a positive correlation with albumin (P less than 0.05); these findings indicate that alpha 2 HS is a negative AP-reactant. In addition, analysis of the principal components confirms thestrong analogy between alpha 2 HS and albumin and indicates that serum level behavior of the AP-reactants during the course of the disease closely depends on the protein studied.

Blood Proteins↗

PubMed1978

Principal clinical features and prognosis in chronic lymphocytic leukemia.

A prospective study of 102 patients with chronic lymphocytic leukaemia (CLL) on 30 parameters subdivided into 77 variables was analyzed by correspondence analysis, a variant of principal component analysis, which allows simultaneous graphical representation of patients and variables. This statistical method clearly defined three principal clinical features recognized at the time of diagnosis: lymph node proliferation, lymphoid infiltration and cytopenia. Cytopenia was clearly subdivided into peripheral and central types. Each of these clinical features were derived from clinical and laboratory observations which agreed with each other. Simple examination permitted an evaluation of these three syndromes. They seemed to be independent of each other except for a relationship between central cytopenia and lymphoid infiltration. Thus clinical staging at the moment of diagnosis must record three scales of severity corresponding to the three independant clinical features. Prognosis was essentially related to cytopenia, whatever the mechanism. In a further analysis of the subsequent progress of the disease, a "common path" for patients was found terminating in a region of the graph where marked splenomegaly and cytopenia were plotted. We conclude that it is necessary to consider the three clinical features independently in a clinical staging. This study emphasizes the poor prognosis of cytopenia and splenomegaly and indicates that follow up and treatment should take this feature into account.

Anemia↗

PubMed2026

Pilot study identifying distinct circulating proteomic profiles associated with longitudinal CT-defined fibrotic and inflammatory sarcoidosis.

INTRODUCTION: Pulmonary sarcoidosis exhibits heterogeneous clinical trajectories ranging from self-limited disease resolution to chronic progressive fibrosis, yet reliable biomarkers capable of distinguishing these disease patterns remain lacking. Whether longitudinal CT-defined sarcoidosis phenotypes are associated with distinct circulating molecular signatures remains unknown. METHODS: We performed high-throughput plasma proteomics (SomaScan 11K) in participants with pulmonary sarcoidosis classified into longitudinal chest CT-defined progressive fibrosis, progressive nodular inflammatory disease, or resolving disease trajectories, along with healthy controls. CT phenotypes were assigned based on predefined longitudinal changes in reticulation, traction bronchiectasis, nodular involvement, and mediastinal lymphadenopathy across serial CT scans. One plasma sample per participant was selected from the study visit corresponding to the CT time point at which criteria for the assigned longitudinal phenotype were met. Principal component analysis, hierarchical clustering, pathway enrichment, and correlation-based analyses linking protein expression to quantitative CT features were used to evaluate whether distinct longitudinal CT phenotypes were associated with divergent proteomic signatures. RESULTS: Principal component analysis and hierarchical clustering suggested partial segregation by CT-defined phenotype. Longitudinal CT phenotypes were associated with distinct pathway-level proteomic signatures, with progressive fibrosis enriched for epithelial-mesenchymal transition signaling, and progressive nodular inflammatory disease enriched for mTORC1, MYC, oxidative phosphorylation, adipogenesis, and fatty acid metabolism pathways. Correlation analyses showed coordinated protein-expression patterns associated with fibrotic CT features and mediastinal lymph node enlargement. DISCUSSION: These findings suggest that longitudinal CT-defined fibrotic and inflammatory sarcoidosis phenotypes are associated with distinct pathway-level proteomic signatures. This pilot study provides preliminary proof-of-concept evidence that integrating longitudinal CT imaging phenotypes with plasma proteomics may serve as a framework for future mechanistic studies and biomarker discovery in pulmonary sarcoidosis.

Humans↗

PubMed1979

A multivariate analysis of fatness and relative fat patterning.

Skinfold measurements (triceps, subscapular, suprailiac and medial calf) in four samples (376 boys, 352 girs, 338 men and 380 women from rural Colombia) were subjected to principal components analysis to identify components of obesity and relative fat patterning. Three components emerged which were similar in the four samples: a first component of fatness explaining 70-80% of the variance and two fat pattern components each explaining 10-15% of the variance: trunk-extremity and upper-lower body. Fatness and the trunk-extremity pattern components changed with age in children (7-12 years), but none of the components changed with age in adults (25-60+). The fatter tended to be more patterned in both age groups. Canonical correlation analysis revealed that socioeconomic status was more related to fatness than to patterning. With the exception of brothers, all first degree relatives (sib, parent-off-spring) and spouses were correlated in fatness. Some of the correlations between relatives--usually sibs, but not spouses--were also significant for the pattern components, suggesting a genetic basis for the known stability of this characteristic (Garn, '55a). Principal components analysis is a useful multivariate alternative for quantitative studies of anthropometric patterning.

Adipose Tissue↗

PubMed2026

Research on identification of key genes and immune-metabolic mechanisms in atrial fibrillation through integrated multi-cohort transcriptomic analysis and machine learning.

This study aimed to integrate multiple datasets for the identification of atrial fibrillation (AF)-related differentially expressed genes (DEGs), analyze their underlying mechanisms through functional enrichment and machine learning, construct diagnostic models, and explore immune-metabolic interactions to provide novel biomarkers and theoretical foundations. Gene expression datasets were integrated and normalized, with batch effects removed using principal component analysis. Differential expression analysis, functional enrichment analysis (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways), and machine learning-based feature gene selection and model construction were performed. Shapley additive explanations analysis was utilized to interpret the constructed models, while gene set enrichment analysis, gene set variation analysis, and immune cell infiltration analysis were conducted to investigate the associations between feature genes and immune infiltration. After integrating and normalizing gene expression data and eliminating batch effects via principal component analysis, 6 DEGs were identified, including 4 upregulated and 2 down-regulated ones. Functional enrichment analysis showed these DEGs were significantly enriched in neuro-related biological processes and pathways, indicating their key roles in AF pathogenesis. Five key feature genes were selected using LASSO, random forest, and support vector machine-recursive feature elimination algorithms. They had significant expression differences between the AF and control groups (P < .001) and were located on distinct chromosomes. The constructed random forest and support vector machine models performed excellently (area under the curve ≥ 0.85). Shapley additive explanations analysis revealed TNNI1 contributed most to model prediction, with its expression significantly positively correlated with immune cell infiltration. Gene set enrichment analysis and gene set variation analysis analyses further showed feature genes participated in AF pathogenesis by regulating immune modulation, metabolic pathways, and autophagy. Immune cell infiltration analysis found altered proportions of T-cell subsets and M0 macrophages in the AF group, along with complex links between feature gene expression and immune cell function. This study systematically elucidated the unique gene expression patterns and key regulatory pathways associated with AF, clarifying the crucial roles of feature genes in immune regulation, metabolic imbalance, and cellular dysfunction. These findings provide a theoretical basis and potential therapeutic targets for understanding AF pathogenesis and developing targeted treatment strategies.

Atrial Fibrillation↗

PubMed2025

Charting the phenotypic landscape of mitochondrial diseases through a systematic evaluation of pathogenic mitochondrial DNA and nuclear gene variants.

PURPOSE: Primary mitochondrial diseases (PMD) arise from variants in the mitochondrial or nuclear genomes. Phenotype-based recognition of specific PMD genotypes remains difficult, prolonging the diagnostic odyssey. We expanded the MitoPhen database to characterize phenotypic variation across PMD more systematically. METHODS: Individual-level data on mitochondrial DNA disorders, nuclear-encoded mitochondrial diseases, and single large-scale mitochondrial DNA deletions were manually curated with Human Phenotype Ontology (HPO) terms to produce MitoPhen v2. Principal-component analysis summarized system-level abnormalities; HPO-level enrichment and mean phenotype-similarity scores were then used to distinguish common PMD genotypes. RESULTS: MitoPhen v2 adds 3940 individuals to the original release, now encompassing 1597 publications, 10,626 individuals, and 117 genotypes. Among 7586 affected cases, 72,861 HPO terms were recorded. Principal-component analysis revealed 6 phenotype dimensions capturing most system-level variance. At the HPO level, we observed genotype-specific enrichments and identified 111 gene-phenotype links absent from the current HPO database. Using MT-TL1, single large-scale mitochondrial DNA deletions, and POLG as exemplars, phenotype-similarity scores reliably separated individuals with these genotypes from those without. CONCLUSION: MitoPhen v2 enabled systematic, genotype-aware analysis of heterogeneous PMD phenotypes and highlighted the diagnostic value of structured, individual-level data. Phenotype-similarity metrics from such data sets can refine variant interpretation in large rare-disease cohorts and provide a transferable framework for other phenotypically complex genetic disorders.

Humans↗

PubMed1992

The Scottish Heart Health Study. Dietary intake by food frequency questionnaire and odds ratios for coronary heart disease risk. II. The antioxidant vitamins and fibre.

High serum antioxidant vitamins are increasingly being associated with reduced risk of coronary heart disease (CHD). Previous studies have not addressed the relationship between dietary antioxidant vitamins and risk of CHD although diet is a key factor which modifies blood antioxidant vitamin levels. In prospective studies, high-fibre diets have also been associated with reduced CHD incidence. In this analysis CHD-diagnosed, -undiagnosed and non-CHD controls were selected from 10,359 men and women aged 40-59 who participated in a cross-sectional study of CHD risk factors. Diet was assessed by food frequency questionnaire, odds ratios were adjusted for the classical CHD risk factors (+/- social class) and calculated relative to the first quintile for each vitamin and total fibre. The antioxidant vitamins were further combined in a principal component analysis and the odds ratios for undiagnosed and diagnosed CHD were again calculated. For undiagnosed CHD, risk was significantly lower in the highest quintiles of beta-carotene, fibre and vitamin C, E and A for men, but only lower for fibre in women. Opposite trends were observed in the odds ratios for vitamin C and E and fibre for male-diagnosed CHD which possibly indicates changes in diet as a result of diagnosis. Principal component analysis showed significantly reduced risk of undiagnosed CHD in the top three quintiles for men (odds ratios 0.66, 0.67 and 0.64; P less than 0.05 in each case). A similar trend occurred for women but was non-significant. The results suggest that high dietary intake of the antioxidant vitamins may reduce risk of CHD, particularly in men, and that fibre may be equally cardio-protective in both sexes.

Adult↗

PubMed2026

[Genetic diversity analysis of Forsythia suspensa germplasm resources in Shanxi based on phenotypic traits and SNP molecular markers].

This study aimed to clarify the degree of fruit phenotypic variation and the characteristics of genetic diversity, population structure, and genetic differentiation of Forsythia suspensa resources in Shanxi, providing an important basis for germplasm conservation and breeding of superior varieties. A total of 46 F. suspensa fruits were collected, and 12 agronomic traits were measured and analyzed. The population genetic structure and genetic diversity of F. suspensa germplasm were evaluated using simplified genome sequencing technology. For the five quality traits of the 46 fruits, the Shannon-Wiener index ranged from 0.631 to 1.074, and the Simpson index ranged from 0.379 to 0.560. The seven quantitative traits exhibited abundant genetic variation, with coefficients of variation ranging from 9.764%(fruit shape index) to 45.494%(forsythin content). Principal component analysis reduced the 12 phenotypic traits to four factors, with a cumulative variance contribution of 74.547%. Sequencing data showed mean Q20 and Q30 values of 98.13% and 94.33%, respectively, with an average GC content of 35.95%. After filtering, a total of 12 347 327 high-quality single nucleotide polymorphism(SNP) loci were obtained. Based on these high-quality SNPs, principal component analysis, population structure analysis, and phylogenetic tree construction were carried out. The 46 germplasm resources were divided into four groups; however, grouping showed little relationship with geographic origin, and intermixing occurred among regions. Mantel test revealed a significant but weak positive correlation between phenotypic and genetic distances(r=0.159, P=0.001). At the molecular level, the four groups exhibited moderate genetic diversity overall, and the genetic differentiation index among populations ranged from 0.027 to 0.084, indicating low to moderate differentiation. The rich genetic diversity of the main phenotypic traits provides a solid material basis for screening superior germplasm and genetic breeding of F. suspensa.

Forsythia↗

PubMed1977

Congenital defects of the upper lateral incisors: multivariate analysis of measurements of the other teeth, the superior arch, head and face.

The survey of a French male population allowed us to ascertain 75 propositi with one or two missing ULI, 59 propositi with one or two reduced ULI and 99 controls on whom measurements (mesiodistal and buccolingual diameters) of all of teeth of the superior arch are available. Principal Component Analysis gave a first estimated principal component highly correlated with each of the dental measurements of arch measurements. This size factor was eliminated by observing the plane of the second and third principal components. Strikingly different clusters of MD diameters or BL diameters were observed for the controls, the propositi missing one or two fo the ULI and the propositi with reduced ULI. For the controls, the arch length is correlated with the MD molar diameters and the MD incisor diameter, the arch width being isolated from the other measurements. For the propositi with missing ULI, among the dental measurements the MD and BL diameters cluster, the arch length is isolated as are the arch widths. For the propositi with reduced ULI, the rich length is closer to the dental measurements while the widths, especially the first one, are isolated. The best discriminant measurements are the diameters of the first premolars and the canine, the first arch width and the arch length. Among controls, the arch is narrowed and shorter for the propositi with absence and wider for the propositi with reduction. Teeth measurements are always smaller in propositi.

Adolescent↗

PubMed2025

MaxComp: Predicting single-cell chromatin compartments from 3D chromosome structures.

The genome is organized into distinct chromatin compartments with at least two main classes, a transcriptionally active A and an inactive B compartment, broadly corresponding to euchromatin and heterochromatin. Chromatin regions within the same compartment preferentially interact with each other over regions in the opposite compartment. A/B compartments are traditionally identified from ensemble Hi-C contact frequency matrices using principal component analysis of their covariance matrices. However, defining compartments at the single-cell level from sparse single-cell Hi-C data is challenging, especially since homologous copies are often not resolved. To address this, we present MaxComp, an unsupervised method, for inferring single-cell A/B compartments based on 3D geometric considerations in single-cell chromosome structures-derived either from multiplexed FISH-omics imaging or 3D structure models derived from Hi-C data. By representing each 3D chromosome structure as an undirected graph with edge-weights encoding structural information, MaxComp reformulates compartment prediction as a variant of the Max-cut problem, solved using semidefinite graph programming (SPD) to optimally partition the graph into two structural compartments. Our results show that the population average of MaxComp single-cell compartment annotations closely matches those derived from ensemble Hi-C principal component analysis, demonstrating that compartmentalization can be recovered from geometric principles alone, using only the 3D coordinates and nuclear microenvironment of chromatin regions. Our approach reveals widespread cell-to-cell variability in compartment organization, with substantial heterogeneity across genomic loci. When applied to multiplexed FISH imaging data, MaxComp also uncovers relationships between compartment annotations and transcriptional activity at the single-cell level. In summary, MaxComp offers a new framework for understanding chromatin compartmentalization in single cells, connecting 3D genome architecture, and transcriptional activity with the cell-to-cell variations of chromatin compartments.

Chromatin↗

PubMed1992

Quality of life consequences of chemotherapy-induced emesis.

Nausea and vomiting following chemotherapy administration are common and often overlooked causes of impairment in cancer patients. The goal of this study was to explore the broad range of consequences associated with this specific acute toxicity of chemotherapy. Specific objectives were: (1) create and test scales specifically designed to assess the impact of chemotherapy-induced nausea and vomiting or patients' daily function; (2) examine changes in quality of life of cancer patients 3 days following chemotherapy administration; (3) assess the impact of chemotherapy-induced emesis on quality of life and patients' daily function; (4) identify medical and non-medical cost-related consequences associated with chemotherapy-induced emesis. Patients receiving intermittent bolus chemotherapy regimens on an outpatient basis were eligible for this survey. Four instruments were used: a patient maintained diary, the Functional Living Index-Cancer (FLIC), a newly created Functional Living Index-Emesis (FLIE) and an Item Check list for cost-related consequences. On Day 1, before chemotherapy, patients completed the FLIC and FLIE. Patients recorded episodes on vomiting, severity of nausea, anxiety, sedation, antiemetics self-administered, and adverse effects in diaries for 3 days following chemotherapy. The FLIC and FLIE were completed at the end of Day 3. The Item Check list of cost-related consequences was administered as a telephone survey on Day 5. Approximately 56% of 122 patients reported chemotherapy-induced emesis (CIE). A change in mean FLIC score indicating a decline in quality of life was observed for the CIE group (119 to 101) but not in the group who did not report emesis (124 to 122). Decline in FLIC and FLIE from before to after chemotherapy administration was greater for CIE patients (p = 0.001). FLIE scores indicated that CIE patients perceived that vomiting, and to a slightly lesser extent, nausea substantively influenced their ability to complete household tasks, enjoy meals, spend time with family and friends, and maintain daily function and recreation. Effect size calculations supported a significant negative relationship between occurrence of CIE and the direction and magnitude of functional living index change. An exploratory analysis (principal component followed by regression analysis) supported the hypothesis that side-effects produced by chemotherapy and antiemetic therapy significantly contributed to changes in quality of life observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Activities of Daily Living↗

PubMed1976

Classification and discrimination for data analysis in pharmacology.

Classification and discrimination are described as methods of inference and decision-making in pharmacological data analysis. Principal components and multiple discriminant analysis are applied to animal and human spectra of the neuroleptics. A preliminary step is required to separate differences in potency from the spectral information.

Animals↗

PubMed1978

[Piracetam and vigilance. A study of EEG changes and clinical effects in gerontopsychiatric patients (author's transl)].

The electroencephalographic and clinical effects of piracetam were studied in a group of 11 hospitalized gerontopsychiatric patients treated with a daily dosage of 4.8 g for 8--13 months. The EEG was evaluated by power spectral analysis, followed by a principal component analysis of frequency parameters. The statistical analysis of the resulting factor scores shows that piracetam induces significant EEG changes: decrease of slow frequencies, augmentation and acceleration of alpha-activity and increase of beta-activity. These EEG changes, indicating an increase in vigilance, correspond clinically to an improvement of communicative behavior and cognitive functioning.

Aged↗

PubMed1978

[On the effect of the antidepressant viloxazin on EEG and optimization of the system driver-vehicle-road (author's transl)].

The effects of a single dose of 100 mg 2-[(o-ethoxyphenoxy)-methyl]-morpholine hydrochloride (viloxazin) on EEG and optimizing control behaviour of drivers were investigated under double-blind conditions in 5 male subjects with many years' driving experience. The study was carried out on a special test course using a car equipped with measuring devices. The following signals were recorded: EEG and EOG, driving speed, steering torque, steering angle and angle rate, longitudinal and lateral acceleration, and yaw rate. As evaluated by means of spectral analysis with a subsequent principal component analysis the EEG showed an increase of the power in alpha- and beta-frequencies indicating a drug induced decrease of EEG vigilance. In correspondence the optimization of the system driver-vehicle-road was reduced indicating an impairment of the driver's control behaviour.

Adult↗

PubMed1977

Correspondence analysis of HLA gene frequency data from 124 population samples.

Correspondence analysis, a variant of principal components analysis, is used to interpret and compare gene frequencies of the HLA system for 124 samples from different populations studied in the Fifth and Sixth International Histocompatibility Workshops. The major advantage of this analysis is that populations and HLA genes are represented simultaneously with respect to the same axes in multidimensional space. This permits the visual interpretation of genetic differences between populations, the relative participation of each gene in the dispersion, and the correspondence between populations and genes. By this method a clear separation of ethnic groups in the world is obtained. Furthermore, within Europe the separation of samples from different countries is concordant with their geographical distances. The HLA system appears sufficiently polymorphic to define a population by its gene frequencies.

Asian People↗