AllelesPolymorphism, GeneticGenotypeGene FrequencyPolymorphism, Single NucleotideGenetic Predisposition to DiseasePolymorphism, Restriction Fragment LengthPolymerase Chain ReactionGenetic VariationMutationPhenotypeHaplotypesHeterozygoteMolecular Sequence DataHomozygoteBase SequenceChromosome MappingLinkage DisequilibriumMicrosatellite RepeatsGenetic MarkersCase-Control StudiesHLA-DRB1 ChainsCrosses, GeneticModels, GeneticGenetics, Population