HLA-DRB1 Chains: A subtype of HLA-DRB beta chains that includes over one hundred allele variants. The HLA-DRB1 subtype is associated with several of the HLA-DR SEROLOGICAL SUBTYPES.HLA-DRB5 Chains: A subtype of HLA-DRB beta chains that is associated with the HLA-DR51 serological subtype.HLA-DRB3 Chains: A subtype of HLA-DRB beta chains that includes over 50 allelic variants. The HLA-DRB3 beta-chain subtype is associated with HLA-DR52 serological subtype.HLA-DR Antigens: A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS.HLA-DRB4 Chains: A subtype of HLA-DRB beta chains that is associated with the HLA-DR53 serological subtype.HLA-DQ beta-Chains: Transmembrane proteins that form the beta subunits of the HLA-DQ antigens.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.HLA-DQ Antigens: A group of the D-related HLA antigens found to differ from the DR antigens in genetic locus and therefore inheritance. These antigens are polymorphic glycoproteins comprising alpha and beta chains and are found on lymphoid and other cells, often associated with certain diseases.HLA-DQ alpha-Chains: Transmembrane proteins that form the alpha subunits of the HLA-DQ antigens.Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.Genetic Predisposition to Disease: A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.Arthritis, Rheumatoid: A chronic systemic disease, primarily of the joints, marked by inflammatory changes in the synovial membranes and articular structures, widespread fibrinoid degeneration of the collagen fibers in mesenchymal tissues, and by atrophy and rarefaction of bony structures. Etiology is unknown, but autoimmune mechanisms have been implicated.HLA-DR beta-Chains: Transmembrane proteins that form the beta subunits of the HLA-DR antigens. They are also referred to as the HLA-DR light chains.Gene Frequency: The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.Histocompatibility Testing: Identification of the major histocompatibility antigens of transplant DONORS and potential recipients, usually by serological tests. Donor and recipient pairs should be of identical ABO blood group, and in addition should be matched as closely as possible for HISTOCOMPATIBILITY ANTIGENS in order to minimize the likelihood of allograft rejection. (King, Dictionary of Genetics, 4th ed)Haplotypes: The genetic constitution of individuals with respect to one member of a pair of allelic genes, or sets of genes that are closely linked and tend to be inherited together such as those of the MAJOR HISTOCOMPATIBILITY COMPLEX.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Peptides, Cyclic: Peptides whose amino and carboxy ends are linked together with a peptide bond forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS. Some of them are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).Epitopes: Sites on an antigen that interact with specific antibodies.Uveomeningoencephalitic Syndrome: A syndrome characterized by bilateral granulomatous UVEITIS with IRITIS and secondary GLAUCOMA, premature ALOPECIA, symmetrical VITILIGO, poliosis circumscripta (a strand of depigmented hair), HEARING DISORDERS, and meningeal signs (neck stiffness and headache). Examination of the cerebrospinal fluid reveals a pattern consistent with MENINGITIS, ASEPTIC. (Adams et al., Principles of Neurology, 6th ed, p748; Surv Ophthalmol 1995 Jan;39(4):265-292)Genes, MHC Class II: Genetic loci in the vertebrate major histocompatibility complex that encode polymorphic products which control the immune response to specific antigens. The genes are found in the HLA-D region in humans and in the I region in mice.HLA-DR4 Antigen: An HLA-DR antigen which is associated with HLA-DRB1 CHAINS encoded by DRB1*04 alleles.HLA-DP beta-Chains: Transmembrane proteins that form the beta subunits of the HLA-DP antigens.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Multiple Sclerosis: An autoimmune disorder mainly affecting young adults and characterized by destruction of myelin in the central nervous system. Pathologic findings include multiple sharply demarcated areas of demyelination throughout the white matter of the central nervous system. Clinical manifestations include visual loss, extra-ocular movement disorders, paresthesias, loss of sensation, weakness, dysarthria, spasticity, ataxia, and bladder dysfunction. The usual pattern is one of recurrent attacks followed by partial recovery (see MULTIPLE SCLEROSIS, RELAPSING-REMITTING), but acute fulminating and chronic progressive forms (see MULTIPLE SCLEROSIS, CHRONIC PROGRESSIVE) also occur. (Adams et al., Principles of Neurology, 6th ed, p903)Rheumatoid Factor: Antibodies found in adult RHEUMATOID ARTHRITIS patients that are directed against GAMMA-CHAIN IMMUNOGLOBULINS.Immunoglobulin Light Chains: Polypeptide chains, consisting of 211 to 217 amino acid residues and having a molecular weight of approximately 22 kDa. There are two major types of light chains, kappa and lambda. Two Ig light chains and two Ig heavy chains (IMMUNOGLOBULIN HEAVY CHAINS) make one immunoglobulin molecule.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Immunoglobulin Heavy Chains: The largest of polypeptide chains comprising immunoglobulins. They contain 450 to 600 amino acid residues per chain, and have molecular weights of 51-72 kDa.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Protein Tyrosine Phosphatase, Non-Receptor Type 22: A subtype of non-receptor protein tyrosine phosphatases that is characterized by the presence of an N-terminal catalytic domain and a C-terminal PROLINE-rich domain. The phosphatase subtype is predominantly expressed in LYMPHOCYTES and plays a key role in the inhibition of downstream T-LYMPHOCYTE activation. Polymorphisms in the gene that encodes this phosphatase subtype are associated with a variety of AUTOIMMUNE DISEASES.HLA-B Antigens: Class I human histocompatibility (HLA) surface antigens encoded by more than 30 detectable alleles on locus B of the HLA complex, the most polymorphic of all the HLA specificities. Several of these antigens (e.g., HLA-B27, -B7, -B8) are strongly associated with predisposition to rheumatoid and other autoimmune disorders. Like other class I HLA determinants, they are involved in the cellular immune reactivity of cytolytic T lymphocytes.HLA-A Antigens: Polymorphic class I human histocompatibility (HLA) surface antigens present on almost all nucleated cells. At least 20 antigens have been identified which are encoded by the A locus of multiple alleles on chromosome 6. They serve as targets for T-cell cytolytic responses and are involved with acceptance or rejection of tissue/organ grafts.Bahrain: An independent state, an archipelago in the western Persian Gulf, northwest of Qatar. It comprises low-lying islands of Bahrain (the largest), Muharraq, Sitra, and several islets. It has extensive oil fields. The name comes from the Arabic al-bahrayn, "the two seas", with reference to its lying in the middle of a bay with its "two seas" east and west of it. (From Webster's New Geographical Dictionary, 1988, p107 & Room, Brewer's Dictionary of Names, 1992, p45)Rheumatoid Nodule: Subcutaneous nodules seen in 20-30% of rheumatoid arthritis patients. They may arise anywhere on the body, but are most frequently found over the bony prominences. The nodules are characterized histologically by dense areas of fibrinoid necrosis with basophilic streaks and granules, surrounded by a palisade of cells, mainly fibroblasts and histiocytes.Uveoparotid Fever: A manifestation of sarcoidosis marked by chronic inflammation of the parotid gland and the uvea.HLA-DR2 Antigen: A broad specificity HLA-DR antigen that is associated with HLA-DRB1 CHAINS encoded by DRB1*01:15 and DRB1*01:16 alleles.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Myosin Heavy Chains: The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.Linkage Disequilibrium: Nonrandom association of linked genes. This is the tendency of the alleles of two separate but already linked loci to be found together more frequently than would be expected by chance alone.HLA Antigens: Antigens determined by leukocyte loci found on chromosome 6, the major histocompatibility loci in humans. They are polypeptides or glycoproteins found on most nucleated cells and platelets, determine tissue types for transplantation, and are associated with certain diseases.Leprosy, Paucibacillary: A form of LEPROSY classified by the World Health Organization for the purpose of treatment, based on clinical manifestations and skin smear results. Patients with paucibacillary leprosy have fewer than six skin lesions with no causative agent MYCOBACTERIUM LEPRAE on any slit-skin smear testing. Paucibacillary leprosy encompasses indeterminate, borderline tuberculoid, and tuberculoid leprosy.Myosin Light Chains: The smaller subunits of MYOSINS that bind near the head groups of MYOSIN HEAVY CHAINS. The myosin light chains have a molecular weight of about 20 KDa and there are usually one essential and one regulatory pair of light chains associated with each heavy chain. Many myosin light chains that bind calcium are considered "calmodulin-like" proteins.HLA-DP Antigens: A group of the D-related HLA antigens (human) found to differ from the DR antigens in genetic locus and therefore inheritance. These antigens are polymorphic glycoproteins comprising alpha and beta chains and are found on lymphoid and other cells, often associated with certain diseases.Histocompatibility Antigens Class II: Large, transmembrane, non-covalently linked glycoproteins (alpha and beta). Both chains can be polymorphic although there is more structural variation in the beta chains. The class II antigens in humans are called HLA-D ANTIGENS and are coded by a gene on chromosome 6. In mice, two genes named IA and IE on chromosome 17 code for the H-2 antigens. The antigens are found on B-lymphocytes, macrophages, epidermal cells, and sperm and are thought to mediate the competence of and cellular cooperation in the immune response. The term IA antigens used to refer only to the proteins encoded by the IA genes in the mouse, but is now used as a generic term for any class II histocompatibility antigen.HLA-D Antigens: Human immune-response or Class II antigens found mainly, but not exclusively, on B-lymphocytes and produced from genes of the HLA-D locus. They are extremely polymorphic families of glycopeptides, each consisting of two chains, alpha and beta. This group of antigens includes the -DR, -DQ and -DP designations, of which HLA-DR is most studied; some of these glycoproteins are associated with certain diseases, possibly of immune etiology.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.HLA-DR3 Antigen: An HLA-DR antigen which is associated with HLA-DRB1 CHAINS encoded by DRB1*03 alleles.Polymorphism, Single Nucleotide: A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.Asian Continental Ancestry Group: Individuals whose ancestral origins are in the southeastern and eastern areas of the Asian continent.Kashin-Beck Disease: Disabling osteochondrodysplasia with OSTEOSCLEROSIS, cone-shaped METAPHYSIS, and shortening of the DIAPHYSIS. It is endemic in parts of Siberia and northern China. Mineral deficiencies (e.g., selenium, iodine), fungal cereal contamination, and water contamination may be contributing factors in its etiology.HLA-DR Serological Subtypes: HLA-DR antigen subtypes that have been classified according to their affinity to specific ANTIBODIES. The DNA sequence analyses of HLA-DR ALPHA-CHAINS and HLA-DR BETA-CHAINS has for the most part revealed the specific alleles that are responsible for each serological subtype.Leprosy, Multibacillary: A form of LEPROSY classified by the World Health Organization for the purpose of treatment, based on clinical manifestations and skin smear results. Patients with multibacillary leprosy have six or more lesions with or without positive skin smear results for the causative agent MYCOBACTERIUM LEPRAE. Multibacillary leprosy encompasses borderline lepromatous, midborderline, and lepromatous leprosy.