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H A Erlich

Publications and source records attributed to H A Erlich.

At least 145 records · Page 8Linked to original sources
PubMed1991

Shared epitopes among HLA class II alleles: gene conversion, common ancestry and balancing selection.

The extent and pattern of HLA class II sequence polymorphism raise a variety of evolutionary questions, notably those concerning the genetic mechanisms for generating diversity, the rate of change and the nature of the selection pressure maintaining this variation. Phylogenetic analysis of primate MHC class II sequences suggests that the allelic lineages are ancient, having diverged long before separation of the hominoid species. For the beta-chain loci, however, considerable allelic diversification within these lineages has occurred after speciation. The striking patchwork pattern of polymorphism with different alleles containing common sequence motifs can be accounted for by common ancestry, by gene conversion or by convergent evolution, depending on the location of the shared epitope.

Alleles↗
PubMed1991

Rapid typing of DNA sequence polymorphism at the HLA-DRB1 locus using the polymerase chain reaction and nonradioactive oligonucleotide probes.

An HLA-DR typing system that uses sequence-specific oligonucleotide (SSO) probes conjugated to horseradish peroxidase (HRP) for analyzing DRB alleles amplified by the polymerase chain reaction has been developed. Using 25 HRP-SSO probes and two primer pairs for generic and for DRB1 locus-specific amplification, we can distinguish 31 of 34 HLA-DRB1 alleles. This procedure is suitable for typing heterozygous samples from a variety of sources, including cDNA templates, and can detect in a simple and rapid dot-blot format allelic variants not distinguishable by serological methods. It should prove valuable for tissue typing, determining individual identity, and studies of disease susceptibility.

Amino Acid Sequence↗
PubMed1991

Molecular analysis of the role of the HLA class II genes DRB1, DQA1, DQB1, and DPB1 in susceptibility to Lyme arthritis.

Using the polymerase chain reaction and sequence-specific oligonucleotide probes, we have determined the distribution of the alleles at the polymorphic class II loci, DRB1, DQA1, DQB1, and DPB1 in 25 patients with Lyme arthritis. Comparison of the frequencies of the DRB1 and DPB1 alleles in Lyme arthritis patients to the Centre d'Etude du Polymorphisme Humaine control panel revealed statistically significant differences between the two groups. An increase in DRB1*1301 is noted along with a unique distribution of the DR4 subtypes within the 9 DR4+ patients. In addition, an increase in the rate DPB1*1001 and the more common DPB1*0201 alleles is reported.

Disease Susceptibility↗
PubMed1991

DNA amplification for DQ typing as an adjunct to serological prenatal HLA typing for the identification of potential donors for umbilical cord blood transplantation.

It has recently been demonstrated that umbilical cord blood from genotypically human leukocyte antigen (HLA)-matched donors can provide sufficient numbers of progenitor cells for hematopoietic reconstitution. This technique has been successfully applied in the treatment of two children affected with Fanconi anemia (FA). Fetal cells from the potential sibling donors were first tested to determine that the fetus was not affected with FA. Unaffected fetal cells were then tested for HLA type. Cord blood from compatible donors can be harvested at birth and used immediately or frozen for subsequent use in hematopoietic reconstitution. We now show that fetal cell DNA amplification and hybridization for DQ typing can be an important adjunct procedure to verify serologically determined HLA class II types and/or to establish class II haplotype identity with the affected sibling.

Blood Transfusion↗
PubMed1991

The evolution of allelic diversity at the primate major histocompatibility complex class II loci.

The evolutionary history of polymorphism at the DQ alpha, DQ beta, and DR beta loci appears to be quite distinct and reflects different genetic mechanisms and selection pressures for the different loci. Phylogenetic analysis of sequences from a variety of species allows the tentative reconstruction of the order of gene duplication and of allelic diversification. Some of the major allelic types or lineages appear to be very old (greater than 20 myr) and selection has acted to maintain these ancient allelic types as well as, in the case of the DR beta loci, to favor new variants generated by recombining beta-sheet and alpha-helix domains. Phylogenetic analysis can also reveal balancing selection at individual residues of the class II beta chains. The highest number of phylogenetically inferred changes attributed to balancing selection was found at beta-chain residues located in the ABS and at those residues implicated in disease susceptibility. For some residues, the number of different amino acids observed at individual polymorphic positions is highly restricted and the few tolerated residues are common to all primate species studied. This observation supports the view that these positions are subject to some form of balancing selection.

Alleles↗
PubMed1991

Oligonucleotide typing is a perfect tool to identify antigens stimulatory in the mixed lymphocyte culture.

An important criterion for the selection of donors for bone marrow transplantation is the grade of matching for HLA between donor and recipient. For patients that lack an HLA-identical sibling, an extending pool of unrelated volunteers for bone marrow donation is available. From these donors the best matched candidate can be selected by serological typing, followed by a mixed lymphocyte culture (MLC). Oligonucleotide genotyping for HLA class II antigens is considered to be valuable for the prediction of MLC reactivity. We investigated whether this typing method, in combination with serological typing, would cover the recognition of all MLC stimulatory determinants. One hundred thirty-six combinations of HLA-A, -B, and -DR serologically identical individuals were tested in the MLC. Additional typing for HLA-DRB and HLA-DPB by oligonucleotide genotyping made it possible to evaluate the influence of these genes on MLC reactivity. Combinations that were matched for HLA-DRB gave significantly lower responses than those that were mismatched. Nevertheless, in the matched combinations responses were observed to 94% relative response index. These responses could all be attributed to HLA-DP, since all combinations that were identical by HLA-DPB genotyping were negative in the MLC. In conclusion, with the combined use of serology and oligonucleotide genotyping, responder-stimulator combinations can be selected that are identical for all MLC stimulatory determinants.

Bone Marrow Transplantation↗
PubMed1991

HLA class II sequences and genetic susceptibility to insulin dependent diabetes mellitus.

The analysis of HLA class II sequence variation in IDDM patients and controls, made possible by the PCR, has revealed that specific alleles are associated with IDDM. The HLA-DQ beta chain appears to play a role in determining genetic susceptibility and resistance, although polymorphisms in the DRB1, the DQ alpha, and the DP beta chain may also contribute. Although there is a correlation between susceptibility and the charge of DQ beta residue 57, the complex genetic epidemiology of IDDM cannot be accounted for by polymorphism at this position. As we have discussed previously (Horn et al, 1988a, 1988b; Erlich et al, 1990b), there are no unique class II sequences associated with IDDM, consistent with the view that 'normal' class II alleles confer susceptibility. Given the estimates of concordance of under 50% for monozygotic twins and approximately 15% (Tattersall and Pyke, 1972; Thomson, 1988) for HLA-identical sibs--it is not surprising that some unaffected individuals contain putative susceptibility alleles. Perhaps some environmental 'triggering' agent, such as viral infection, is required for the disease to develop in susceptible individuals. Other non-MHC-linked genes which contribute to susceptibility may account for the difference in concordance rates for monozygotic twins and for HLA-identical sibs. In the NOD (non-obese diabetic) mouse and the BB rat models for IDDM, non-MHC susceptibility loci have been identified and mapped (Colle et al, 1981; Hattori et al, 1986) but, in humans, the analysis of non-MHC candidate loci (i.e. the T cell receptor) has, thus far, failed to reveal any other susceptibility loci. In general, the HLA-linked genetic susceptibility to IDDM, as well as to other autoimmune diseases, appears to be associated with specific combinations of class II epitopes (e.g. alleles, haplotypes or genotypes) rather than with specific individual residues or epitopes. Understanding the role of these predisposing sequences will require structural analysis of the class II molecules as well as in vitro and in vivo functional studies of interactions with putative autoantigens and T cell receptors. In the meantime, DNA typing offers the potential for identifying individuals at high risk. These susceptible individuals could be monitored by immunological (e.g. anti-islet cell antibody) or by metabolic tests to detect the preclinical phase of IDDM.

Amino Acid Sequence↗
PubMed1991

Implication of specific DQB1 alleles in genetic susceptibility and resistance by identification of IDDM siblings with novel HLA-DQB1 allele and unusual DR2 and DR1 haplotypes.

Genetic susceptibility to insulin-dependent diabetes mellitus (IDDM) is associated with the HLA-DR3 and DR4 haplotypes. The HLA-DR2 haplotype is negatively associated with IDDM, an association that has been interpreted as dominant protection. Here, we describe the molecular analysis of the HLA class II genes in an unusual family with three HLA-DR1/2 siblings, all of whom have IDDM. With polymerase chain reaction amplification and sequence analysis to characterize the class II alleles, we identified a novel DQB1 allele on the DR1 haplotype and an unusual DQB1 allele on the DR2 haplotype. However, the DRB1 alleles on these DR1 and DR2 haplotypes are the conventional alleles (*0101 and *1501, respectively). These results suggest that it is the conventional DQB1 allele (*0602) not the DRB1 allele (*1501) on the protective DR2 haplotype that confers protection in the general population and, furthermore, that these unusual DQB1 alleles may confer susceptibility to IDDM in this family. The unusual DQB1 allele on this DR2 haplotype encodes Asp at position 57, indicating that it is the allele DQB1*0602 and not simply the presence of this residue that is responsible for the protective effect.

Adolescent↗
PubMed1991

Km typing with PCR: application to population screening.

The immunoglobulin kappa light chain (IgK) locus may play a significant role in the pathology of both infectious and autoimmune diseases. Most of the work on IgK genetics has been conducted using immunological techniques for allelic typing and sequence analysis. This is restricted by availability of reagents and can be both expensive and time-consuming. PCR primers were designed to amplify the kappa constant gene (Ck), and four allele-specific oligonucleotides (ASOs) were used to distinguish the alleles in the amplified PCR products. Direct sequencing of PCR products was performed to confirm that the primers specifically amplified the Ck region and the ASOs differentiated the Km alleles. Sequencing of an average of 209 nucleotides of DNA from 50 individuals revealed no variation except at codon 191, which is known to be involved in a frequent polymorphism. An analysis of 347 different individual DNAs from 10 human populations was conducted to determine Km allelic frequencies within these populations and to apply this type of data collection to population studies.

Alleles↗
PubMed1991

Population variation of human mtDNA control region sequences detected by enzymatic amplification and sequence-specific oligonucleotide probes.

A method for detecting sequence variation of hypervariable segments of the mtDNA control region was developed. The technique uses hybridization of sequence-specific oligonucleotide (SSO) probes to DNA sequences that have been amplified by PCR. The nucleotide sequences of the two hypervariable segments of the mtDNA control region from 52 individuals were determined; these sequences were then used to define nine regions suitable for SSO typing. A total of 23 SSO probes were used to detect sequence variants at these nine regions in 525 individuals from five ethnic groups (African, Asian, Caucasian, Japanese, and Mexican). The SSO typing revealed an enormous amount of variability, with 274 mtDNA types observed among these 525 individuals and with diversity values, for each population, exceeding .95. For each of the nine mtDNA regions significant differences in the frequencies of sequence variants were observed between these five populations. The mtDNA SSO-typing system was successfully applied to a case involving individual identification of skeletal remains; the probability of a random match was approximately 0.7%. The potential useful applications of this mtDNA SSO-typing system thus include the analysis of individual identity as well as population genetic studies.

Base Sequence↗
PubMed1990

Limited heterogeneity of rearranged T-cell receptor V alpha transcripts in brains of multiple sclerosis patients.

The identification of activated T cells in the brain of individuals with multiple sclerosis (MS) indicates that these cells are critical in the pathogenesis of this disease. In an attempt to elucidate the nature of the lymphocytic infiltration, we used the polymerase chain reaction to amplify T-cell antigen receptor (TCR) V alpha sequences from transcripts derived from MS brain lesions. In each of three MS brains, only two to four rearranged TCR V alpha transcripts were detected. No V alpha transcripts could be found in control brains. Sequence analysis of transcripts encoded by the V alpha 12.1 region showed rearrangements to a limited number of J alpha region segments. These results imply that TCR V alpha gene expression in MS brain lesions is restricted.

Base Sequence↗
PubMed1990

HLA class II polymorphism and genetic susceptibility to insulin-dependent diabetes mellitus.

As we have discussed previously (Horn et al. 1988a; Erlich et al. 1989b; Horn et al. 1988b), there are no unique class II sequences associated with IDDM, which suggests that "normal" class II alleles confer susceptibility. Given the estimates of concordance--under 50% of monozygotic twins and approximately 15% (Tattersol, Pyle 1972 and Thomson 1988) for HLA-identical sibs--, it is not surprising that some unaffected individuals contain putative susceptibility alleles. Perhaps some environmental "triggering" agent, such as viral infection (Yoon, this volume), is required for the disease to develop in susceptible individuals. Other non-MHC linked genes which contribute to susceptibility may account for the difference in concordance rates for monozygotic twins and for HLA-identical sibs. In the nonobese diabetic mouse and the BB rat models for IDDM, non-MHC susceptibility loci have been identified and mapped (Hattori et al. 1986; Colle et al. 1981), but in humans the analysis of non-MHC candidate loci (i.e., the T cell receptor) has thus far failed to reveal any other susceptibility loci. In general, the HLA-linked genetic susceptibility to IDDM, as well as to other autoimmune diseases, appears to be associated with specific combinations of class II epitopes (e.g., alleles, haplotypes, or genotypes) rather than with specific individual residues or epitopes. Understanding the role of these predisposing sequences will require structural analysis of the class II molecules as well as in vitro and in vivo functional studies of interactions with putative autoantigens and T cell receptors. In the meantime, DNA typing offers the potential for identifying individuals at high risk for IDDM.

Diabetes Mellitus, Type 1↗
PubMed1990

Rapid HLA-DPB typing using enzymatically amplified DNA and nonradioactive sequence-specific oligonucleotide probes.

A simple and rapid method for characterizing the polymorphism at the HLA-DPB1 locus has been developed. The procedure involves the selective amplification of the polymorphic second exon of the DPB1 locus by the polymerase chain reaction (PCR), followed by hybridization of the amplified DNA with 15 nonisotopic sequence-specific oligonucleotide probes. There are no sequences within the second exon of the DPB1 locus that uniquely define an allele; rather, each allele appears to arise from the shuffling of a limited number of polymorphic nucleotide sequences in six regions of variability. Consequently, individual alleles are identified by the pattern of hybridization of the 15 probes. Two formats for typing are described. In Format I (the dot-blot), the amplified DNA is ultraviolet (UV) cross-linked to a nylon membrane and hybridized with the oligonucleotide probes which are covalently labeled with horseradish peroxidase (HRP). In Format II (the reverse dot-blot), the oligonucleotides, which have poly-T tails, are bound to the membrane and the immobilized array of probes is hybridized to the PCR product which has incorporated biotinylated primers during the amplification process. In both formats, hybridization is detected by a simple colorimetric reaction. The application of this technology to the fields of tissue typing and individual identity is discussed.

Alleles↗