WMDA Directory

HLA Nomenclature in WMDA file format

At the request of the IT Working Group (now Bioinformatics and Innovation Committee) of the World Marrow Donor Association (WMDA) the IPD-IMGT/HLA Database makes a number of computer readable files available. These files will document the official WHO HLA Nomenclature, the relationships between serologically defined antigens, and relationships between HLA allele sequences and their serologically defined antigens. Updated versions of these files will be released every three months, at the same time as new versions of the IPD-IMGT/HLA Database become available.

These files are based on formats originally defined by the WMDA IT Working Group and built in collaboration with the WHO Nomenclature Committee for Factors of the HLA System.

Following the publication of the 2026 HLA Nomenclature Report, the IPD-IMGT/HLA Database continues to actively work with the WHO Nomenclature Committee for Factors of the HLA System, and the developers of the HATS algorithm to update and provide this data to our users. The recent nomenclature introduces some new serological definitions and associated antigens. The impact on files is limited to the hla_nom.txt, rel_ser_ser.txt, and rel_dna_ser.txt files which are often imported for the validation of serological values and for confirming potential serological values for new alleles.

These files are made available from the IMGTHLA GitHub repository which contains files from the most recent IPD-IMGT/HLA Database release on the Latest branch, and all previous releases in branches named by the release version. For example the 3.63.0 release is available on the 3630 branch.

For more detailed information on the contents of these files, and details of recent changes, please refer to the WMDA README file in our public GitHub repository.

File Headers

All five files have a short header with six lines of information, indicating:

• File Name
• Date file produced (YYYY-MM-DD)
• Version (IPD-IMGT/HLA Version Number)
• Origin of file (URL)
• Repository (URL)
• Author

These lines all start with a hashtag (#) to indicate they represent comments or metadata and not the main content. If additional comments are required these will be added between the header lines and the main data and the line will start with a hashtag (#).

Files undergoing development will have the following lines added:

• Disclaimer

hla_nom.txt

Download the hla_nom.txt file here.

This file contains details of all current and deleted HLA antigens and alleles, and is sorted by locus and antigen/allele number:

• HLA Locus
• HLA Antigen or Allele name
• Date assigned (YYYYMMDD)
• Date deleted, if the name has now been abandoned (YYYYMMDD)
• Antigen or Allele that the deleted allele was shown to be identical to
• Reason for the Antigen or Allele to be deleted

Please note that for HLA Antigen names assigned before November 1987, the dates given are only approximate.

This file includes six fields of information, each separated by a semi-colon (;).

Following publication of the latest HLA Nomenclature Report in 2026, the following changes can be seen in the hla_nom.txt file:

• Additional lines have been added for the new antigen specificities and new associated antigens.

hla_nom_g.txt

Download the hla_nom_g.txt file here.

HLA alleles that have identical nucleotide sequences across the exons encoding the peptide binding domains (exon 2 and 3 for HLA class I and exon 2 only for HLA class II alleles) will be designated by an upper case ‘G’ which follows the first 3 fields of the allele designation of the lowest numbered allele in the group. The full list of these groups is available at the G Groups page. A computer readable version is also available, this file includes three fields of information, each separated by a semi-colon (;).

Following publication of the latest HLA Nomenclature Report in 2026, there are no changes to this file.

hla_nom_p.txt

Download the hla_nom_p.txt file here.

This file contains details of all HLA Sequences having the same antigen binding domains. This analysis is performed on the polypeptide sequence, and for HLA Class I alleles, identity in the "antigen binding domains" is based on identical protein sequences as encoded by exons 2 and 3. For HLA Class II alleles this is based on identical protein sequences as encoded by exon 2. HLA alleles having nucleotide sequences that encode the same protein sequence for the peptide binding domains (exon 2 and 3 for HLA class I and exon 2 only for HLA class II alleles) will be designated by an upper case P which follows the 2 field allele designation of the lowest numbered allele in the group. The full list of these groups is available at the P Groups page. A computer readable version is also available, this file replaces the file previously called abdm.txt and includes three fields of information, each separated by a semi-colon (;).

Following publication of the latest HLA Nomenclature Report in 2026, there are no changes to this file.

rel_ser_ser.txt

Download the rel_ser_ser.txt file here.

This file lists the relationships between all current serologically defined HLA antigens: broad antigens, split antigens and associated antigens.

• HLA Locus
• HLA Antigen name
• Split Antigen
• Associated Antigen

This file includes four fields of information, each separated by a semi-colon (;). The file lists only those antigens for which split or associated antigens exist. Multiple values are separated by a forward slash (/).

Following publication of the latest HLA Nomenclature Report in 2026, the following changes can be seen in the rel_ser_ser.txt file:

• Existing three digit associated antigen designations will be extended to four digits by adding a leading zero e.g. 203 to 0203 on the line starting A;2
• The lists of associated antigens for each broad or split specificity will be extended where new associated antigens have been assigned e.g. the line A;2;;203/210 will now be listed as A;2;;0201/0202/0203/0208/0210/0211/0216/0218/0219/0220/0244/0246/0256/0265/0285
• Additional lines will be added where a broad specificity now has associated antigens e.g. the A;3;;0301/0305/0323, will be added between the lines starting A;2 and A;9 lines. This represents forty-nine new lines added to the file

rel_dna_ser.txt

Download the rel_dna_ser.txt file here.

This file contains details of all current HLA alleles and where known their unambiguous, possible or assumed serologically equivalent antigens. This file is provided as a tool for the validation of HLA typing data at the request of the WMDA, explicitly for the cross checking of data where both a serological HLA antigen and a DNA based HLA allelic typing is also present.

Details of the unambiguous serology is defined from submissions to the WHO Nomenclature Committee for Factors of the HLA System (1) at the time an allele is submitted for naming, from the WMDA HLA Dictionary 2008 (2), or for some alleles from the HATS algorithm assignments (1,3). For Null alleles a value of zero "0" is given and for alleles with no corresponding antigen a question mark "?" is given.

In cases where an allele has been shown to be associated with more than one serologically defined antigen, these are indicated in the "Possible Serology" field. Multiple values are separated by a forward slash (/). In cases where there is currently no information about the serological equivalent of an allele, the "Assumed Serology" field contains the antigen equivalent as expected by the first two digits of the allele name. It is entirely possible that the "Assumed Serology" may contain information that is later shown to be incorrect when the serologically defined antigen is characterised.

As indicated above this file is produced solely as a tool for the validation of existing HLA serological and DNA based allelic typing data and is not produced to infer the serological typing of alleles which have not been experimentally characterised.

1. Marsh SGE, Osoegawa K, Bodmer WF, et al. Nomenclature for Factors of the HLA System, 2026. HLA (2026) 107:e70595
2. Holdsworth R, Hurley CK, Marsh SGE et al. The HLA Dictionary 2008: a summary of HLA-A, -B, -C, -DRB1/3/4/5, -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR and -DQ antigens. Tissue Antigens (2009) 73 95-170
3. https://github.com/kosoegawa/HATS

This file contains details of all current HLA antigens and alleles, and is sorted by locus and allele number:

• HLA Locus
• HLA Allele Name
• Unambiguous Serological Antigen associated with allele, as assigned by WHO Nomenclature Committee and described above.
• Possible Serological Antigen associated with allele, where multiple serologies are reported
• Assumed Serological Antigen associated with allele
• Expert assigned exceptions in search determinants of some registries
• Assigned specificity as calculated by HATS for those alleles with a Full or Serotype sequence classification.

This file includes seven fields of information, each separated by a semi-colon (;).

Following publication of the latest HLA Nomenclature Report in 2026, the following changes can be seen in the rel_dna_ser.txt file:

• The addition of an additional column to provide information assigned by the HATS algorithm (https://github.com/kosoegawa/HATS). This column will include either an associated antigen, split, broad or be left blank as determined by the algorithm.
• Any existing three digit associated antigen designations will be extended to four digits by adding a leading zero e.g. 203 to 0203
• The values in the third to sixth fields representing Unambiguous, Possible, Assumed or Expert assigned antigens associated with the allele may be updated to reflect any new assignment. Any values used would be consistent with the latest nomenclature report.

md5checksum.txt

Download the md5checksum.txtfile here.

This file contains an md5 fingerprint for each file allowing verification of the downloads.

The release archive is now maintained as a git repository and available at https://github.com/ANHIG/IMGTHLA. This repository contains a branch for each database release and a Latest branch which contains the most recent files as well as all compressed archives.

Pre-2026 WMDA Files

In addition the following files are now available in the pre2026 sub-folder of the IMGTHLA GitHub repository. This directory contains copies of the hla_nom.txt, rel_ser_ser.txt and rel_dna_ser.txt using any definitions prior to the 2026 HLA Nomenclature Report. These files are provided purely for testing purposes and comparison against the new files. These are intended to aid in any work migrating systems to use the new definitions and are not intended for long term or clinical usage.

• (1) Nomenclature for Factors of the HLA System, 2026.
• SGE Marsh, K Osoegawa, WF Bodmer, RE Bontrop, MN Carrington, HA Erlich, S Heidt, R Holdsworth, WR Mayr, M Maiers, P Parham, EW Petersdorf, J Robinson , J Trowsdale, M Fernández-Viña
• HLA. 2026 107:e70595 (Download PDF)

• (2) The HLA Dictionary 2008: a summary of HLA-A, -B, -C, -DRB1/3/4/5, -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR and -DQ antigens.
• Holdsworth R, Hurley CK, Marsh SGE et al.
• Tissue Antigens. 2009 73 95-170 (Download PDF)