The HLA gene regulates our acquired immune system. It is what helps our body identify foreign antigens (bacteria, fungi, viruses) and determine what type of white blood cells and antibodies should be produced. Depending on our HLA type we are more or less resistant to certain diseases and infections. HLA also influences our risk of developing autoimmune diseases like diabetes, multiple sclerosis, rheumatism, arthritis, hypothyroidism, psoriasis, Celiac disease, Crohn's disease, fibromyalgia, and so on.
Class I HLA (A, B and C) deal with intracellular immunity, i.e. mostly viruses and some bacteria (e.g. Chlamydia, Rickettsia, Mycobacteria, Mycoplasma). Class II HLA (DM, DO, DP, DQ, DR) fight off extracellular pathogens - mostly bacteria and fungi. HLA DM to DQ have little diversity, so the main determinant of extracellular immunity between individuals is above all HLA-DR. HLA-DR is subdivided in HLA-DRA (3 variants) and HLA-DRB (439 variants), but all useful variations are found within HLA-DRB, which has 23 types usually in European/Caucasian people. The short-hand HLA-DR always refers to HLA-DRB.
You can compare the distribution of HLA-DR alleles by country to get a better idea of where each type is more common. To better visualize regional variations, I have started making maps for each HLA-DR type. Here are those that I have already made: HLA-DR1, HLA-DR3, HLA-DR4, HLA-DR7, HLA-DR11, HLA-DR15, HLA-DR16.
You can know your HLA types through a blood test, i.e. serotype (ask your doctor), or checking the raw from your DNA, i.e. genotype, if you tested with 23andMe, and in some cases also with Geno 2.0 or FamilyFinder. Some alleles are not tested by any of the three companies though. I have found a list of SNPs for all common European types, but unfortunately I do not know which allele is positive for some SNPs. If some of you have more information, make sure to share it.
There are subtypes for each HLA-DR type, although most of them have only one common subtype in Europe. HLA-DRB*0101 means essentially the same as HLA-DR1. To be more accurate it is subtype 1 of HLA-DR1, but it is the only subtype found in Europe. The highest diversity of subtypes in found within HLA-DR4, although non-Mediterranean Europeans usually belong to HLA-DRB*0401. The positive allele is indicated in brackets/parentheses. You will need to be positive for all SNPs listed in the same row to belong to one HLA-DR type. Each person normally belongs to two HLA-DR types (although it is possible to have twice the same). The most common subtypes are indicated in bold.
I have tried to geographically match the colours of HLA types to the colours I used for Y-DNA haplogroups. For example, HLA-DR9 is most common in North Asia and among Finno-Ugric people, so I used purple like for Y-haplogroup N1c. HLA-DR11 peaks in West Asia, Greece and Italy, so I used green like for Y-haplogroup J2. I couldn't always find a correlation with Y-DNA, so I sometime used colours used for mtDNA or autosomal maps, as in HLA-DR15 which is orange like the ANE admixture.
HLA-DR Type
SNP 1 SNP 2 SNP 3 HLA-DRB*0101
rs4947332 (T) rs6457614 (G) HLA-DRB*0301
rs2040410 (A) HLA-DRB*0401 rs6910071 (G) rs3817964 (A) rs660895 (G) HLA-DRB*0402
rs3130071 (T) rs416352 (T) HLA-DRB*0403 rs7454108 (C) rs206765 rs399604 HLA-DRB*0404
rs2736157 (G) rs3115572 (C) rs2395533 HLA-DRB*0405
rs1057149 (A) HLA-DRB*0407 rs7774197 (C) rs417812 HLA-DRB*0701 rs7745002 rs2647087 rs241398 HLA-DRB*0801 rs7743506 HLA-DRB*0901 rs2395185 (T) rs2516049 (C) HLA-DRB*1001 rs4148871 (A) rs2071538 (A) HLA-DRB*1101 rs434841 (A) rs1061172 rs5875439 (I) HLA-DRB*1103 rs4639334 (A) rs412735 rs210180 (A) HLA-DRB*1104 rs4713607 (G) rs12664430 (T) HLA-DRB*1201 rs6901541 (C) rs6916742 HLA-DRB*1301 rs2395173 (A) rs2157051 (C) HLA-DRB*1302 rs4434496 (T) rs6901541 (C) HLA-DRB*1303 rs424232 (T) rs2050191 (A) HLA-DRB*1401 rs2763979 (T) rs1794265 (C) HLA-DRB*1404 rs805262 (T) rs1794265 (C) HLA-DRB*1501 rs3135388 (T) HLA-DRB*1601 rs3129891 (A) rs6923504 (G)
Note that HLA-DR2 doesn't exist anymore. It was split into DR15 and DR16. Likewise HLA-DR5 was split in HLA-DR11 and HLA-DR12, while HLA-DR6 was divided in HLA-DR13 and HLA-DR14.
Depending on reading directions your DNA test, the letters of the alleles might different. Just remember that C=G and A=T.