HLA-DP variation as additional risk factor in IDDM.

A significant increase in the frequency of DPw3/6 alleles defined by restriction-fragment-length polymorphism is observed in insulin-dependent diabetes mellitus (IDDM) patients relative to healthy control subjects (34.6 vs. 10.5%, P less than 0.009). Log-linear modeling demonstrates that this association is independent of HLA-DR3 and -DR4 and IDDM association and cannot be attributed to linkage disequilibrium between HLA-DP and -DR. The analysis also demonstrates an absence of interactive effects among the antigens in conferring IDDM susceptibility. The strength of the DPw3/6 association is not significantly less than that of either DR3 or DR4.

Strong association of HLA-DR3/DRw9 heterozygosity with early-onset insulin-dependent diabetes mellitus in Chinese.

Studies of Caucasian and Japanese patients with insulin-dependent diabetes mellitus (IDDM) have shown that heterozygosity for certain HLA-DR antigens confers a high risk of developing the disease. The HLA antigens of 75 Chinese patients and 100 Chinese controls in Hong Kong were studied to investigate the role of HLA-DR heterozygosity in Chinese individuals. Some of the patients and controls were also tested for allotypic variation in the complement components C2, C4, and BF. Three alleles, Aw33, B17, and DR3, had increased frequencies in patients compared with controls and frequently occurred together in the same phenotype, which suggested their existence as a haplotype. There were no statistically significant differences in complement allotype frequencies between patients and controls, although the C4B null allele seemed to be associated with Aw33, B17, and DR3. No other HLA-DR antigen appeared to be associated with IDDM. However, when the patients were separated on the basis of age at onset, the frequency of DR3/DRw9 heterozygosity was markedly increased in patients presenting in the first decade of life, but there was no increase in patients presenting at greater than 20 yr of age. DRw9 is strongly associated with autoimmune disease in Chinese, whereas DR3 is not. We suggest that the major IDDM susceptibility locus in Chinese is associated with HLA-DR3 and that patients with HLA-DR3 and HLA-DRw9 have an added predisposition to autoimmune disease and therefore develop IDDM earlier than patients without DRw9.

Normal coding sequence of insulin gene in Pima Indians and Nauruans, two groups with highest prevalence of type II diabetes.

The nucleotide sequence of the insulin gene was determined in American Pima Indians and Micronesian Nauruans, two populations in whom the prevalence of non-insulin-dependent (type II) diabetes mellitus is the highest in the world. The insulin gene was amplified by the polymerase chain reaction to generate single-stranded DNA suitable for direct sequencing. The nucleotide sequences of the coding and adjacent regions of the insulin gene in six Pima Indians and two Nauruans with type II diabetes were identical to previously published insulin gene sequences of nondiabetic subjects.

Diversity in HLA-DR4-related DR,DQ haplotypes in Australia, Oceania, and China.

The relative distributions of 12 HLA-DR4-related DRB1 alleles in indigenous populations of Australia, Melanesia, Micronesia, Polynesia, and northern and southern China have been determined by analysis of oligonucleotide hybridization patterns of 406 examples of HLA-DR4. DRB1*0405 and DRB1*0410 were common DR4 alleles in Australian aborigines and in Melanesians, while DRB1*0403 was the predominant DR4 allele in coastal Melanesians, Micronesians, and Polynesians; DRB1*0406 was confined to Chinese. A novel DR4 allele, found in 30% of DR4-positive Australian aborigines but exclusive to one aboriginal population, was a combination of DRB1*04 and 0803 nucleotide sequences and was carried on a haplotype with DR4-like DQ linkage arrangements. DQA1 and DQB1 typing generated 12 DR4-related haplotypes; the population distributions of these reflected the ancestral affinities of aborigines and Melanesians, the overlaying of coastal Melanesia with pre-Polynesian DR4 alleles and the colonization of Micronesia by an independent, non-Polynesian group. DR4-related autoimmune disorders such as rheumatoid arthritis (RA) and insulin-dependent diabetes mellitus (IDDM) are virtually unknown in indigenous populations of Australia and Oceania and this study confirmed that high-risk RA determinants, Dw4 and Dw14, occurred rarely. However, the DQw8 allele, thought particularly to predispose to IDDM, was present in the majority of DR4-positive Polynesians and Micronesians.

HLA-DR,DQ sequence polymorphisms in Polynesians, Micronesians, and Javanese.

The origins of the Polynesians remain an enigma. Linguistic reconstructions of proto-Austronesian languages suggest a shared origin for Polynesians, Micronesians, and Javanese with dispersal from northern Borneo and Sulawesi. Analysis of 810 chromosomes for nucleotide sequence polymorphism at HLA-DRB1, DRB3, DRB5, DQA1, and DQB1 loci in Polynesian (Rarotonga, Western Samoa, and Niue), Micronesian (Nauru and Kiribati), and Javanese populations showed virtually no overlap of HLA class II haplotypes between contemporary Polynesians and Javanese. Further, there were marked differences in population distributions of some HLA-DRB1 alleles that could not be distinguished in earlier serologic or restriction fragment length polymorphism (RFLP) studies, e.g., for DR12, DRB1*1201 had a frequency of 15%-30% in Polynesians (1% in Micronesians and Javanese), whereas DRB1*1202 had a frequency of 28%-38% in Micronesians and 51% in Javanese (1% in Polynesians). A novel DR6-related allele, DRB1*1408, was found in all three Polynesian study populations. The Polynesian HLA class II genetic repertoire is not readily derived from the island Southeast Asian gene pool.

Characterization of the HLA-A polymorphism by locus-specific polymerase chain reaction amplification and oligonucleotide hybridization.

This report describes a PCR-based typing protocol for the HLA-A polymorphism. Locus-specific primers selectively amplified HLA-A sequences from exon 1 to exon 3 in a single PCR that avoided co-amplification of other classical and nonclassical class I genes. The allelic variation in exons 2 and 3 of the HLA-A gene was examined with a set of 44 oligonucleotide probes. According to the recognized HLA-A sequences the protocol is potentially able to distinguish all known HLA-A alleles with unique nucleotide sequences in this gene region. The related HLA-A genotypes can also be identified in both homozygous and heterozygous individuals. Thus the protocol provides the highest resolution for HLA-A typing. The PCR-SSO typing technique is accurate, reliable, and particularly suitable for a large number of samples. The DNA typing results from 42 Tenth IHWS B-cell lines are compatible with the serologic and IEF definitions. Sixty-six unrelated donors from a northern Chinese population were also tested, with 16 HLA-A alleles detected. Four subtypes of HLA-A2 were found in this population. The distribution of HLA-A subtypes in the population indicated that 40% of donor-recipient pairs thought to be matched for HLA-A by serology would be mismatched. Two novel HLA-A alleles were identified by unusual oligonucleotide hybridization patterns.

HLA-DR beta gene DNA polymorphisms revealed by Taq I correlate with HLA-DR specificities.

Human genomic DNA digested with restriction endonuclease Taq I was hybridized with cDNA probes for DR beta and DQ beta, for correlation of restriction fragment length polymorphisms with HLA-DR specificities. DR beta Taq I RFLPs were distinctive for DR serological types 1 to w9, with the exception of DR3 and w6, and were markedly consistent within DR specificity. Some common variants in RFLPs did emerge within serological type; DR3, e.g., was associated with two different fragment patterns, one of which occurred on the A1.B8.DR3 haplotype and was linked with a DR alpha Bgl II variant, and the other on the B18.DR3 haplotype. In the Pacific specimens examined, RFLPs were, with few exceptions, similar to those seen in Caucasoids sharing the same DR specificity. This study indicates that genomic hybridization is a useful adjunct to serological and cellular class II typing and should be particularly informative in identifying new HLA-DR alleles in populations serologically less well-defined than Caucasoids.

RFLP-defined HLA-DP polymorphism in four ethnic groups.

Patterns of BglII, MspI, and TaqI DP alpha and DP beta hybridizing restriction fragment length polymorphisms are compared with primed lymphocyte typing--determined specificities in 28 10th International Histocompatibility Workshop core cell lines. Correlation of specific RFLP patterns with most recognized DP types is confirmed, although the RFLPs do not distinguish DPw3 from DPw6. Analysis of DP-region nucleotide sequence data shows that the observed RFLPs are those expected to hybridize to the DP alpha and beta probes and are thus not due to cross-hybridization to other genes. The distribution of RFLPs in Chinese, Micronesian, South Indian, and white Australian populations is described. The most frequent DP specificity in Chinese is DPw5. In the other populations DPw4 is the most common specificity, although DPw5 is also relatively common in Micronesians. Four new DP alpha RFLP patterns and three new DP beta patterns are described. There are also numerous unusual combinations of DP alpha and DP beta alleles particularly in the South Indian population.

HLA-DQ genotypes are associated with autoimmunity to glutamic acid decarboxylase in insulin-dependent diabetes mellitus patients.

This study has investigated the genetic basis of the heterogeneous autoimmune response to glutamic acid decarboxylase (GAD) in 179 Australian patients with IDDM. Antibodies to GAD have been correlated with HLA-DQB1 alleles and genotypes, as determined by sequence-specific oligonucleotide hybridizations after polymerase chain reaction was applied to exon 2 of the DQ beta 1 gene. HLA-DQ2 was significantly increased (p < 0.01) in IDDM patients with antibodies to GAD. Antibodies to GAD were detected in 64% of 72 DQ2.8 patients, in 55% of 29 DQ2.2 or DQ8.8 patients and in 41% of 78 patients with other HLA-DQB1 genotypes. HLA-DQ genotype association with autoimmunity to GAD was statistically significant (p = 0.02) and reflected early formation of antibodies to GAD, rather than an HLA association with persistence of antibodies to GAD, since the genotype effect was more evident (p = 0.02) in those with more recent onset (0-5 years) of IDDM. Also, the HLA-DQ genotype effect was more evident in patients with IDDM onset after the age of 14 years (p = 0.003). Multivariate analysis showed that HLA-DQB1 genotypes had a more significant impact on antibodies to GAD than either duration or age of onset of IDDM. In patients with IDDM in childhood, only a minority had low-risk HLA-DQB1 genotypes (37%) when compared with those with onset in adulthood (62%) (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

HLA-DR and -DQ DNA polymorphisms: new linkage relationships established by RFLP genomic typing in Polynesians and Melanesians.

Class II restriction fragment length polymorphisms (RFLPs) of DR beta, DQ beta, and DQ alpha loci were examined in Polynesians of the southwest Pacific and in non-Austronesian-speaking Melanesians from the Papua New Guinean Highlands. Polynesians, previously considered to have a restricted set of HLA-DR antigens, showed class II gene heterogeneity associated with DR2, DR5, DRw6, and DRw8 RFLPs. Furthermore, Melanesians and Polynesians share certain antigens such as DRw6 and DRw8, but the DR beta 2 genes associated with DRw6 and the DQ genes associated with DRw8 are population-specific and show little or no overlap. This study has shown that genetic analysis of closely linked polymorphic genes is a powerful anthropological tool and supports the view that Polynesians represent an independent colonizing group in the Pacific, rather than a group evolved from within Melanesia.

HLA-DR, -DQ DNA genotyping and T-cell receptor RFLPs in leprosy.

HLA-DR and -DQ restriction fragment length polymorphisms (RFLPs) were examined in Melanesian leprosy patients and controls from New Caledonia. This permitted DNA subtyping of DQw1, a broad serological specificity previously implicated in predisposition to lepromatous leprosy. The DQw1c subtype, found in linkage disequilibrium with DR1, w10, w14, and some Pacific Island variants of DRw6 and DRw8, was significantly reduced in leprosy patients. Since the association between HLA-DR genes and leprosy is not strong, some candidate non-MHC genes for leprosy susceptibility were examined also. T-cell receptor -alpha, -beta, and -gamma gene RFLPs revealed no germ-line defects or major clonal T-cell expansion in either lepromatous or tuberculoid leprosy patients. The human homologue of the murine Ity locus which determines murine susceptibility to Mycobacterium lepraemurium was sought by examining linkage disequilibrium with RFLPs in the human gamma-crystallin genes, since this gene family forms a syntenic group with isocitrate dehydrogenase-1 in both mouse and man and, in the mouse, this cluster is closely linked to the Ity locus. These RFLPs were not associated with leprosy susceptibility in man.

Distribution and co-occurrence of MHC class I, II, and III markers in southern Chinese: implications for autoimmune disease.

A study of MHC class I, II, and III markers in a group of southern Chinese in Hong Kong is reported. HLA antigen frequencies and complement allele frequencies are given, together with statistically significant pair-wise co-occurrences. Over half of the statistically significant positive and negative linkage disequilibria relate to two extended haplotypes. These haplotypes, or components of them, are associated with a number of diseases in Chinese, particularly diseases of autoimmune origin. One haplotype, A2, Bw46, DRw9, appears to be an analogue of the haplotype A1, B8, DR3 which predisposes to similar diseases in Caucasians. The question is raised of why susceptibility to the same group of diseases in two different racial groups should be related to the haplotypes having the strongest linkage disequilibria within those racial groups.

HLA-DRw15 is increased in frequency in Japanese scleroderma patients.

HLA-DRB allogenotypes were compared in 18 Japanese scleroderma patients and healthy Japanese controls. HLA-DRw15 was found to be significantly increased in frequency in the patient series compared to controls (chi 2 = 4.25, p less than 0.05, Yates' corrected); in DRw15 positive individuals the relative risk of developing scleroderma was 4.0. In Caucasoids DRw11 is significantly associated with scleroderma (Dunckley et al., 1989) and sequence data shows that DRw11 and DRw15 DRB molecules (together with DRw8 where the relative risk of developing scleroderma in Caucasoids is 2.1) share the same amino acid sequence at position 67-70 in the first domain. This would suggest that the DRB1 locus may well be the primary disease promoting locus in scleroderma.

Insulin-dependent diabetes mellitus: HLA-DR and -DQ genotyping in three ethnic groups.

Human genomic DNA samples from Caucasoids, Chinese, and Koreans of known serological DR antigen specificity were studied for IDDM-associated variation in HLA-DR and -DQ RFLPs (restriction fragment length polymorphisms). Genotyping allowed for accurate assignment of HLA-DR types and in Caucasoids DRw6 as well as DR2 was unequivocally decreased in IDDM. Further, the universality of certain DR2-associated DQ beta subtypes in protection against IDDM was established. HLA-DR3 was found to be increased in IDDM irrespective of whether carried on the B8. DR3 or B18. DR3 haplotype in Caucasoids or on the Bw58. DR3 haplotype in Chinese. These haplotypes have different DR alpha and DX alpha arrangements, so the region of susceptibility is confined to DQ alpha, DQ beta. For HLA-DR4, a 12kb/DQ beta/Bam HI fragment was increased in Caucasoid IDDM, but since this fragment is haplotype specific in Caucasoids and occurs in most healthy DR4- and w9-positive Asians, the 12 kb fragment may be a marker for a DR beta subtype of DR4 associated with IDDM in Caucasoids only. This study has shown the value of ethnic comparisons of HLA-associated diseases, where different linkage disequilibrium relationships have permitted identification of common susceptibility determinants and have provided evidence for some heterogeneity between Caucasoid and Asian populations, in the genetics of IDDM.

HLA-DR and -DQ DNA genotyping in insulin-dependent diabetes patients in South India.

Restriction fragment length polymorphisms (RFLPs) of the HLA-DR beta, -DQ alpha, -DQ beta, and -DX alpha genes have been examined in South Indian diabetic patients and controls. The DR. DQ linkage arrangements in South Indians were shown to be different for DR2, DR4, and DRw6 from those commonly seen in Europeans, so that localization of the primary disease-promoting gene in IDDM could be attempted. This study clearly implicates at least one DQ beta allele in the pathogenesis of IDDM.

HLA, complement C2, C4, properdin factor B and glyoxalase types in South Indian diabetics.

A series of diabetic patients from 3 centres in South India have been tested for HLA A, HLA B, BF, C2, C4A, C4B and GLO types. For insulin-dependent diabetes mellitus (IDDM) patients there was a significant increase in HLA B8, of BF F and decrease of C4 A6. No significant variation in HLA, BF, C2 or GLO frequencies was found in non-insulin-dependent diabetes mellitus (NIDDM) patients, but there was a significant decrease in C4B 1 and an increase in C4B 2. The HLA and BF association in South Indian IDDM patients is very different from that reported previously in North India.

The ethnic distribution of antibodies to glutamic acid decarboxylase: presence and levels of insulin-dependent diabetes mellitus in Europid and Asian subjects.

Our objective was to ascertain the frequency of antibodies to glutamic acid decarboxylase (GAD) in Europids and four Asian ethnic groups with insulin-dependent diabetes mellitus (IDDM) to gain insight into why the prevalence and incidence of IDDM varies so widely among ethnic and/or geographically diverse population groups. The subjects in this study were Europid (n = 49), Japanese (n = 16), Thai (n = 7), Korean (n = 21), and Chinese (n = 13) persons with IDDM with a duration ranging from 5 to 14 years. There were similar numbers of healthy controls matched for each ethnic group. A validated radioimmunoprecipitation assay used GAD from pig brain radiolabeled with 125I using chloramine T. Islet cell cytoplasmic antibodies measured by indirect immunofluorescence were expressed as Juvenile Diabetes Foundation units. The prevalence of antibodies to GAD, compared with Europids (63%), was much lower in all Asian populations with IDDM: Japanese (31%), Thai (29%), Korean (5%), and Chinese (27%). The mean level of antibodies to GAD, however, among diabetics from each population who gave a positive reaction, was similar. For all groups, the prevalence of antibodies to GAD was much higher than that of islet cell cytoplasmic antibodies. Almost all IDDM subjects positive for islet cell antibodies had antibodies to GAD, but the converse did not hold. A radioimmunoprecipitation assay for antibodies to GAD applied to serum from subjects with IDDM in various ethnic groups showed that Europids with IDDM had a much higher prevalence of such antibodies than did Asians. This held for all ethnic groups, and particularly Koreans. Thus, among different populations, there may be etiologic heterogeneity of IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic and environmental influence in the epidemiology of noninsulin-dependent diabetes mellitus: a global perspective.

Refinement of the classification of diabetes mellitus to include two major categories, insulin dependent (IDDM) and noninsulin-dependent (NIDDM) and the recent attention paid to the standardization of epidemiological techniques have led to much new information on the epidemiology of the disease. Support for the notion of genetic influence in the development of NIDDM has come from twin studies, but the search for specific genetic markers for NIDDM has been largely unproductive to date. There is increasing scepticism as to the utility of the chlorpropamide-alcohol flush as a genetic marker for NIDDM. The large disparity in the frequency of NIDDM between populations provides indirect support for the genetic hypothesis, as do recent studies of the association between NIDDM and ancestral genetic admixture. Obesity has long been considered a causal factor in the aetiology of NIDDM, though the strength and consistency of this relationship is now being questioned. The strength of the association between obesity and NIDDM has been shown to vary depending on the presence or absence of a family history of the disease. There is further preliminary evidence to suggest that association between obesity and NIDDM may vary in strength between populations, and between the sexes. Little evidence has so far emerged for a role of quantitative or qualitative aspects of diet in the aetiology of NIDDM. This may be due, in part, to the imprecision of current techniques for dietary estimation.(ABSTRACT TRUNCATED AT 250 WORDS)

A selective advantage for the Gerbich-negative phenotype in malarious areas of Papua New Guinea.

The Gerbich-negative phenotype occurs in about 10% of Melanesians living in the northern provinces of Papua New Guinea where malaria is endemic. The prevalence and severity of malaria was determined in 266 Melanesians of known Gerbich blood group status. P. falciparum and/or P. vivax infection in Gerbich-negative subjects was 5.7% compared with 18.6% in those who were Gerbich positive (p = 0.05), whereas P. malariae occurred at comparable rates in Gerbich-negative (8.6%) and Gerbich-positive subjects (8.2%). Gerbich-negative erythrocytes showed increased deformability compared with Gerbich-positive cells, suggesting at least one mechanism by which a selective advantage for the Gerbich-negative phenotype could be effected in malarious areas.

HLA and disease in Oceania.

HLA-A, -B and -DR gene frequency distributions in populations of Australia, Melanesia, Micronesia and Polynesia are examined in relationship to known HLA and disease associations in other populations. With the exception of a correlation between Reiter's syndrome and B27, other HLA and disease associations are markedly absent. Recombinant DNA and cellular subtyping analyses suggest that the HLA-DR subtypes predominating in susceptibility to several autoimmune disorders in Caucasoids are rare in Oceania. The high frequency of serum complement component C4A deficiency in Australian Aborigines may explain the high prevalence of systemic lupus erythematosus in this group.