HLA

HLA Associations with Disease
HLA Marker	Associated Disease(s)	Notes
HLA-B27	Seronegative spondyloarthropathies Ankylosing spondylitis Reactive arthritis Psoriatic arthritis IBD-associated arthritis	MHC class I association strongly linked to seronegative arthropathies
HLA-DR3	Type 1 diabetes mellitus SLE Graves disease Hashimoto thyroiditis Addison disease	Often paired with DR4 in T1DM; linked to multiple autoimmune endocrinopathies
HLA-DR4	Rheumatoid arthritis Type 1 diabetes mellitus Addison disease	Also associated with DR3 in T1DM; key marker in RA susceptibility
HLA-DR2	Multiple sclerosis Hay fever SLE Goodpasture syndrome	Mixed autoimmune + hypersensitivity conditions; MS, SLE, Goodpasture
HLA-DQ2 / DQ8	Celiac disease	“DQ2/DQ8 = Celiac you ate” mnemonic; screen in gluten-sensitive patients
HLA-DR5	Pernicious anemia Hashimoto thyroiditis	Autoimmune thyroid disease marker; also linked to B12 deficiency
HLA-A3	Hemochromatosis	Classic association with hemochromatosis; high yield board linkage
HLA-B8	Myasthenia gravis Graves disease Addison disease	Common in autoimmune polyendocrine syndromes; memory mnemonic: “8 = autoimmune great”
MHC Class I: HLA-A, HLA-B, HLA-C MHC Class II: HLA-DP, HLA-DQ, HLA-DR