Frequencies of gene variant CCR5-Δ32 in 87 countries based on next-generation sequencing of 1.3 million individuals sampled from 3 national DKMS donor centers

Homozygous carriers of CCR5-Delta 32, a gene variant of CC-type chemokine receptor 5 (CCR5), are highly resistant to infections with human immunodeficiency virus type 1 (HIV-1) and therefore preferred stem cell donors for HIV-infected patients. We analyzed CCR5 typing data of 1,333,035 potential hematopoietic stem cell donors enlisted with three national DIMS donor centers. Allele and genotype frequencies were determined for 87 countries of origin as self-assessed by the donors. CCR5-Delta 32 allele frequencies ranged from 16.4% in the Norwegian sample to 0 in donors from Ethiopia. The highest CCR5-Delta 32/Delta 32 genotype frequency was found in the sample from the Faroe Islands (2.3%), whereas in 27 samples, predominantly of donors from Africa, Asia and South America, none of the individuals carried this genotype. The characteristic CCR5-Delta 32 allele frequency decline from Northern to Southeastern Eurasia supports findings of earlier studies. With available HLA haplotype frequency information for the patient's ethnicity, our data allows upfront estimation of the probability that an HLA-matched donor with CCR5-Delta 32/Delta 32 genotype can be found for a patient in need of hematopoietic stem cell transplantation.