What ACKR1 (Duffy Blood Type) Means in My 23andMe Raw Data

ACKR1 (Duffy) in 23andMe raw data usually means rs2814778; CC is the common Duffy-null genotype and may explain a benign lower neutrophil count. It is not a disease by itself. It is a common inherited red-cell variant that can be associated with a lower routine neutrophil count against standard reference ranges in some people, without being an immune deficiency on its own.

What does ACKR1 Duffy mean in my 23andMe raw data?

Open your raw 23andMe file and search for rs2814778 or ACKR1. The line you are looking for is the one where the genotype column reads CC, CT or TT. This marker is the common Duffy blood group variant. Duffy is a blood group system, like ABO or Rh, but most blood tests never mention it.

The ACKR1 gene makes a protein called atypical chemokine receptor 1, also called DARC. It sits on red blood cells. The CC genotype at rs2814778 is the common genetic basis of Duffy-null, but it is not an absolute phenotype. Rare ACKR1 variants exist, and blood-bank testing is required for transfusion decisions.

Here is how to read the raw genotype:

The table is for the common variant that 23andMe tests. It is not a complete blood bank workup. The marker rs2814778 is a common marker, not a full blood-bank phenotype, and rare ACKR1 variants may not be captured by a consumer chip.

The mechanism: why a red-cell protein can be linked to a lower white count

ACKR1/DARC binds chemokines, small immune signalling proteins. In Duffy-null people, that binding capacity is reduced. The link to lower circulating neutrophils is not fully settled. One hypothesis is that altered chemokine handling changes how neutrophils are distributed or measured, but this is not proven. When present, the lower count is usually real on the machine and tends to be stable over time.

A CC genotype at rs2814778 means a low neutrophil count can be a normal variant, not a warning sign by itself. It should be read against the right reference range and clinical context.

This is a recessive pattern. You need two C copies for the full Duffy-null effect. One C and one T does not produce the full Duffy-null pattern. Most CT carriers have blood counts that look normal.

What you would actually see on a CBC

A routine complete blood count may show total white blood cells a little below the lab range. The flagged number is usually the absolute neutrophil count. Many labs use reference ranges that flag mildly low adult neutrophil counts. Some Duffy-null people can have neutrophil counts below typical lab cutoffs, so the result can look worrying while being stable and normal for them. For context, an adult absolute neutrophil count below about 1.5 x 10^9/L may be flagged in some labs, but ranges vary and this is not diagnostic.

What you usually do not see is low hemoglobin or low platelets. The pattern is isolated low neutrophils, stable over months or years, in a person without unusual infections. That is the benign picture.

Things that support this being Duffy-null: - Raw genotype is CC. - Neutrophils are low, but hemoglobin and platelets are normal. - No frequent or unusual infections. - The low count has been stable across repeat tests.

Things that should not be blamed on Duffy-null alone: - Very severe neutropenia. - Fever, mouth ulcers, recurrent pneumonia, or unexplained infections. - A sudden drop from a previously normal high count.

Does Duffy-null mean I have a weak immune system?

No. The common mistake is to treat a low neutrophil count as an immune deficiency. Duffy-null is not that by itself. Neutrophils still work. Duffy-null by itself is not the same as an immune deficiency. Fever, recurrent infections, or new symptoms still need clinical evaluation.

The same variant comes with a possible benefit. Plasmodium vivax malaria uses the Duffy protein to enter red cells. Without the protein, the parasite has a much harder time. That is one reason the variant is common in parts of Africa and in people of African ancestry, and why a low count in a healthy person is usually the wrong thing to chase.

When the simple answer does not hold

CC at rs2814778 does not explain every low white count. You can carry Duffy-null and still have an unrelated reason for neutropenia, such as a recent virus, a medication, an autoimmune process, or low B12. If your count is severe, new, or accompanied by symptoms, it needs a proper workup, not a genotype answer.

The reverse also matters. A CT or TT genotype at rs2814778 does not fully rule out rare Duffy-null alleles, and rs2814778 alone is not a complete blood-group phenotype. If your 23andMe genotype is CT or TT, this marker is probably not why your neutrophils are low. If you have a rare Duffy-null allele that the chip does not test, the raw data can look unremarkable while blood bank phenotyping would still find Duffy-null. For blood transfusion purposes, rely on blood bank testing.

Practical next step: bring the raw genotype and your CBC results to a clinician, and repeat the CBC/differential before drawing conclusions.

healthosx.com/dna

The download steps for 23andMe, on the page itself.

healthosx.com/dna

The short version: what is worth acting on, first.

To see this in your own numbers, open your raw 23andMe, AncestryDNA, MyHeritage or whole-genome VCF file in the free browser-based HealthOS DNA tool. HealthOS reports ACKR1 (Duffy) as one of its single-variant health findings. Whole-genome VCFs without rsID annotations can be used for ancestry but cannot produce the ACKR1 health finding because named positions are required. The raw file is parsed locally in your browser; the full report opens after a one-time emailed code; any ancestry analysis runs on the server only with explicit consent.