HLA-C

HLA-C or Major Histocompatibility Complex is a class I human leukocyte antigen gene. HLA genes help the "immune system distinguish the body's own proteins from proteins made by foreign invaders such as viruses and bacteria". HLA-C is also known as D6S204, HLA-JY3, HLAC, HLC-C, MHC, or PSORS1.

Function
As with other proteins produced from class I genes, proteins produced by HLA-C are found on the surface of almost all cells, and display these protein fragments (peptides) to the immune system. The immune system then identifies any proteins it recognizes as foreign (such as viral or bacterial peptides), and triggers the destruction of the cell.

HLA associations are considered "hallmarks of autoimmune disease". Different variations in HLA-C have been linked to alopecia areata, psoriatic arthritis, susceptibility to psoriasis and susceptibility to HIV type 1.

ME/CFS
A Norwegian study by Lande et al. (2020) found two HLA associations that were more common in people with ME/CFS, with 19.2% of ME/CFS patients carrying one of the two HLA associations identified, compared to 12.2% of the control group. The HLA associations more common in ME/CFS patients were HLA-C*07:04 and HLA-DQB1*03:03. The 426 ME/CFS patients in the study met the Canadian Consensus Criteria for ME/CFS, except for four who met the International Consensus Criteria for ME.

A small Norwegian trial by Rekeland et al. (2020) found patients positive for HLA-DQB1*03:03 and/or HLA-C*07:04 were more likely to respond to cyclophosphamide than patients without those alleles, 83 vs. 43%.

Notable studies

 * 2020, Human Leukocyte Antigen alleles associated with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) (Full text)
 * 2020, Intravenous Cyclophosphamide in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. An Open-Label Phase II Study (Full text)
 * 2021, Fine mapping of the major histocompatibility complex (MHC) in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) suggests involvement of both HLA class I and class II loci (Full text)

Learn more

 * HLA-C - Genetics home reference - US Library of Medicine
 * Histocompatibility complex - Genetics home reference - US Library of Medicine