allelefrequencies.net

What It Is

The Allele Frequency Net Database (AFND) is a non-profit academic database jointly maintained by the University of Liverpool and the Royal Liverpool University Hospital in the UK. Launched in 2003, it focuses on storing and retrieving frequency data for immune-related genes across different populations worldwide. Its core coverage includes Human Leukocyte Antigen (HLA), Killer-cell Immunoglobulin-like Receptors (KIR), MHC class I chain-related genes (MIC), and a variety of cytokine gene polymorphisms.

Core Features

The site offers frequency searches at three levels: allele, haplotype, and genotype. It currently holds about 164,000 HLA frequency records and around 6,731 KIR records, drawn from over 1,800 population studies covering more than 14 million individuals. Notable features include HLA/KIR frequency searches, rare allele searches, low-resolution data queries, KIR genotype searches, and dedicated modules such as HLA and adverse drug reactions (HLA-ADR) and KIR–disease associations. The data uses a "Gold-Silver-Bronze" quality grading system, allowing users to assess data reliability. It also supports Automated Access and data uploads, so researchers can contribute their own population data and publish a Short Population Report (SPR) in Human Immunology on that basis.

Pricing

Completely free and open, with no payment required to search. Operations are sustained by sponsorship from the TxMiller Foundation and diagnostics-industry companies such as Fujirebio, CareDx, Omixon, One Lambda, and Immucor.

Pros and Cons

Its strengths are strong authority, an enormous volume of data, clear citation standards (the 2020 Nucleic Acids Research update), and synchronization with the IMGT/HLA naming standard, making it a standard reference resource for immunogenetics and transplant matching research. The downsides: the interface remains in an early web style with a dated interaction experience; the underlying KIR data is out of date (IPD-KIR is still on the 2015 version); only English is available, with no Chinese support; and scraped pages can have character-encoding garbling. A second major update—the first in twenty years—is currently underway and is expected to address these issues.

Who It's For

Suitable for researchers in immunogenetics, transplant immunology, population genetics, and pharmacogenomics, as well as clinical HLA matching laboratories. The barrier is high for general users—proper use of the query tools and interpretation of results requires a professional background.

Access from China

As a publicly accessible database hosted by an academic institution, it is generally reachable via direct connection with no obvious blocking, though access speeds may be somewhat slow since the servers are located in the UK.