Polymorphism and phylogeny of dinucleotide repeats in human T-cell receptor Vb6 genes

The nonfunctional allele TCRBV6S1B is strongly associated with Helicobacter pylori infection

To determine genetic susceptibility factors for Helicobacter pylori infection, polymorphic T-cell receptor gene elements were investigated in 203 H. pylori-infected individuals and 180 uninfected individuals (controls). H. pylori infection is highly associated with individuals homozygous for the nonfunctional TCRBV6S1B element (odds ratio = 5.9; chi(2) = 13; P = 0.00032; P value corrected for multiple comparisons [Bonferroni correction] = 0. 00063).

Susceptibility to relapsing-progressive multiple sclerosis is associated with inheritance of genes linked to the variable region of the TcR beta locus: use of affected family-based controls

We tested the hypothesis that susceptibility to relapsing-progressive (RP) (but not to relapsing-remitting [RR]) multiple sclerosis (MS) is associated with a gene linked to the TcR beta-chain variable region delimited by the Vbeta8-BamHI and Vbeta11-BamHI RFLP alleles in DRw15+ MS patients, using a contingency-table test of patient data and affected family-based controls. Control alleles and haplotypes were composed of parental marker alleles and haplotypes not transmitted to the affected child, in 90 simplex and 31 multiplex families from British Columbia. A total of 6,164 alleles at 11 loci were segregated through families of probands with RP MS or RR MS. The Vbeta8-Vbeta11 subhaplotype frequencies in the DRw15+ RP MS (but not RR MS) patients differed from control frequencies, because of an increase of the 2-1 subhaplotype (P=.02). Vbeta8-BamHI and Vbeta11-BamHI allele frequencies (P=.05 and .009, respectively) in the DRw15+ RP MS (but not RR MS) patients differed from control frequencies. The Vbeta1-Vbeta8 subhaplotype frequencies in the DRw15- RP MS (but not RR MS) patients differed from control frequencies (P=.03), with a significantly increased frequency of the 1-1 subhaplotype (P=.01; RR=7.1) in RP MS versus RR MS patients. Susceptibility to RP MS is associated both with a recessive inheritance of a gene linked to the 3' (Vbeta11) end of the 2-1 subhaplotype defined by the Vbeta8-BamHI and Vbeta11-BamHI alleles in DRw15+ patients and with a gene, located on the 1-1 subhaplotype, defined by the Vbeta1-TaqI and Vbeta8-MspI alleles of the TcR beta-chain complex in DRw15- patients.

T-cell receptor BV6S1 null alleles and HLA-DR1 haplotypes in polyarticular outcome juvenile rheumatoid arthritis

JRA is a complex of disease subtypes which are normally identified by clinical features such as age of onset and extent of joint involvement both at onset and during the course of the disease. We previously identified an association between TCR BV6S1 null allele and one subgroup of early-onset pauciarticular patients positive for HLA-DQA1*0101, an HLA haplotype predisposing to a polyarticular course of the disease. In this report we extend this observation by identifying an increased prevalence of this nonfunctional or null allele in the patients with a polyarticular disease course regardless of the mode of onset. This increase was most prominent in clinical subsets that have early onset of the disease and a polyarticular outcome. In one clinical group, stratification of patients by the HLA allele DQA1*0101 strengthened the association considerably. This implies that there is an increased genetic load defined by specific alleles of both MHC and TCR genes.

Familial Hypertrophic cardiomyopathy with Wolff-Parkinson-White syndrome maps to a locus on chromosome 7q3

We have mapped a disease locus for Wolff-Parkinson-White syndrome (WPW) and familial hypertrophic cardiomyopathy (FHC) segregating in a large kindred to chromosome 7 band q3. Although WPW syndrome and FHC have been observed in members of the same family in prior studies, the relationship between these two diseases has remained enigmatic. A large family with 25 surviving individuals who are affected by one or both of these conditions was studied. The disease locus is closely linked to loci D7S688, D7S505, and D7S483 (maximum two point LOD score at D7S505 was 7.80 at theta = 0). While four different FHC loci have been described this is the first locus that can be mutated to cause both WPW and/or FHC.

Immunoprinting: various genes are associated with increased risk to develop rheumatoid arthritis in different groups of adult patients

To identify genes that contribute to the manifestation of rheumatoid arthritis we performed association studies via microsatellite analyses of immunorelevant loci (HLA-DRB, 5 T cell receptor loci, TNFa IL1, IL2, IL5R and CD40L). A total of 183 patients and 275 healthy controls were typed in terms of HLA and grouped according to the known predisposing HLA-DRB1 genes (DRB1*04; relative risk approx. 5; DRB1*01, relative risk approx. 2; a third group carried neither allele). Microsatellite polymorphisms characterizing the TCRBV6S3, CD3D, IL1A, IL2, and IL5R genes did not show significant associations with rheumatoid arthritis, whereas TCRBV6S1, TCRBV6S7, TNFa, and CD40L genes may influence relative protection or risk in certain groups of patients. Analysis of a microsatellite marker adjacent to the transcription element alpha (TEA) in the T cell receptor alpha delta complex indicates that in the cohort carrying neither the DRB1*04 nor the DRB1*01 allele the relative risk to acquire rheumatoid arthritis is increased (> 13) or decreased (< 0.07), depending on the inherited microsatellite allele adjacent to the TEA locus. Sequence analysis of the closely linked TEA region from patients and controls revealed a novel dimorphism. Only the newly identified TEA allele leads to binding of a nuclear protein that may be involved in the regulated expression of the TCRDA genes. Subsequent typing of rheumatoid arthritis patients and controls revealed, however, that the association of the microsatellite marker is largely independent of the TEA allele, confirming incomplete linkage in the 2 kb region of the TCRDA locus. These results are discussed in the context of hot spots of recombination in this genomic region and other linked candidate sequences that predispose to develop rheumatoid arthritis.

Genetic analysis of low V beta 3 expression in humans

While studying the T cell receptor (TCR) repertoire of normal individuals, we found that more than 20% of adults have low levels of circulating V beta 3.1+ T cells in both CD4 and CD8 populations. A similar frequency was found in fetal cord blood samples, suggesting that in most cases, the V beta 3.1low phenotype is inherited. In support of this conclusion, children expressing low levels were only found in families where one of the parents expressed this phenotype. In two large families, genetic studies showed that low expression was a recessive trait and dependent on inheritance of particular TCR VB gene complexes. Family members with the low phenotype, however, expressed VB3.1 genes with normal sequences and expressed normal levels of receptor per cell. Results from these families suggest that up to 50% of normal individuals may carry a VB3.1 allele that is defective in its ability to rearrange effectively. In another large family, low expression in one individual was shown not to be determined by genes within the TCR VB gene or major histocompatibility complexes, suggesting a different mechanism for low V beta 3.1+ T cells. Overall, our results describe novel mechanisms that result in low levels of V beta 3.1+ T cells in a relatively large subset of the normal human population.

The extent of the human germline T-cell receptor V beta gene segment repertoire

An assessment of the size of the human TCRBV gene segment repertoire based on the identification of TCRBV gene segments in genomic DNA was undertaken. PCR amplification from cloned and uncloned genomic DNA sources, nucleotide sequencing, Southern blot hybridization, and cosmid cloning were used to identify TCRBV gene segments in multiple unrelated individuals. The key advantages to this approach were: 1) TCRBV gene segments which are expressed only at very low levels in cDNA libraries were still detectable, and 2) it was possible to discriminate between alleles at the same locus vs products of different loci. A total of 63 unique TCRBV gene segments were identified and sequenced. Six of these TCRBV gene segments had not been previously described. Thirty-four cosmid clones containing 51 of the 63 identified TCRBV gene segments were isolated and screened for the presence of additional novel TCRBV subfamily members. These results, obtained by a variety of complementary approaches, indicate that the human TCRBV germline repertoire encodes at least 63 TCRBV gene segments of which 52 are functional. The availability of the majority of these TCRBV gene segments on cosmid clones should facilitate further investigation of germline TCRBV gene segment polymorphism and putative disease associations.