Diamond-Blackfan anemia

Bone marrow is the spongy tissue inside bones that makes blood. In Diamond-Blackfan anemia it fails at one job in particular: making red blood cells. White cells and platelets are usually normal at diagnosis, though low counts in those can appear later.

The name changed recently. In 2024 an international panel of 53 experts from 27 countries adopted “Diamond-Blackfan anemia syndrome” to cover the full range of presentations — including people who carry one of the genes but have never been anemic at all.

Most people are diagnosed as babies. The median age at presentation is around three months, and roughly 90% become symptomatic in the first year of life. But later childhood and adult presentations exist, and so do people found only through genetic testing. “Usually presents in infancy” is accurate; “always” is not.

Most cases come from a change in one copy of a gene that codes for a ribosomal protein. Ribosomes are the machines inside every cell that read genetic instructions and build proteins, and ribosomal proteins are their structural parts. Having one working copy of the gene is not enough — that is the whole mechanism.

Around 70% to 80% of people have an identifiable genetic cause; for the rest no gene has been found yet. The most common single gene is RPS19, at about a quarter of cases, with a long tail of others each accounting for a few percent or less.

Why red cells specifically is not settled science. The favoured explanation is that when ribosomes are scarce, the genetic messages that are hardest to read suffer most — and the master switch that drives red cell development happens to be one of the hardest to read. That is a leading hypothesis, not a closed question.

Inheritance is usually autosomal dominant, meaning one altered copy is enough and an affected person has a 50% chance of passing it on. But roughly 55% to 60% of those cases arise new in that child rather than being inherited from a parent.

More than half of people have at least one physical difference present from birth, and about a quarter have more than one — most often affecting the face and head, the thumb, the kidneys and urinary tract, or the heart. There are tendencies linked to particular genes, but they are tendencies rather than rules.

The immediate effect is anemia: pallor in the skin, gums or nail beds, fatigue, poor feeding in a baby, a fast or irregular heartbeat, breathlessness, cold hands and feet. In infancy, severe untreated anemia is dangerous.

For most people the red cell failure is lifelong. Some later develop low white cells or low platelets as well, and failure across more than one cell line is one of the recognised reasons a team starts talking about transplant.

Iron overload is a consequence of the treatment rather than of the disease. Every red cell transfusion delivers iron the body cannot excrete, and it accumulates in the liver, heart and hormone-producing organs — which is why iron-removing medicine runs alongside long-term transfusion.

Diamond-Blackfan anemia is also a cancer predisposition syndrome, and that shapes care for life. The North American registry has reported an elevated rate of cancers overall, with the strongest signals for myelodysplastic syndrome, acute myeloid leukemia, colorectal cancer and bone sarcoma, at a median age at cancer diagnosis of 41.

There are three mainstays — corticosteroids, regular red cell transfusion, and an allogeneic transplant using marrow or blood stem cells from another person — with iron chelation running alongside transfusion.

Steroids are usually started at twelve months or later. That delay is deliberate: early steroid use impairs growth, which is already a concern here. Response is judged after ten to fourteen days by looking for a rise in young red cells. Around 60% to 80% of people respond initially, and around 30% to 40% stay on steroids long term with a lasting response.

The 2024 consensus lowered the ceiling on long-term steroid dose, and the implication matters: if a child needs more than that to stay off transfusions, the guidance is to stop the steroids and transfuse instead. The reason is the accumulated cost of steroids across a childhood — impaired growth, thinning bones and fractures, cataracts and glaucoma, high blood pressure, diabetes, infection risk.

Transfusion is roughly every three weeks, and the same consensus raised the target hemoglobin level, moving away from more restrictive earlier practice. Iron removal starts after about ten transfusions or at the first evidence of iron loading, and the consensus recommends starting earlier and pushing harder than was previously usual.

A transplant is the only treatment that replaces the failing marrow. Gene therapy — correcting a person’s own stem cells — was still preclinical as of the most recent review we read, with early trials anticipated. It is not an available treatment.

Most families meet this in the first months of a baby’s life, often after a baby is investigated for pallor, poor feeding or breathlessness.

The decision that follows is usually not cure versus no cure. It is which chronic burden to carry: daily or alternate-day steroids and their side effects, or a transfusion roughly every three weeks plus ongoing iron removal.

Treatment independence does happen, and it is worth naming. In a French registry analysis of 222 treated patients, 21% reached it — about 30% among those who had responded to steroids, about 5% among those who had not — and roughly 70% of those who get there do so in the first decade of life.

The 2024 consensus deliberately calls this “clinical remission” rather than remission, for two reasons: it often does not last, and the cancer risk continues regardless. The same consensus retired the term “silent carrier”, renaming it “DBA syndrome currently without phenotype”, on the reasoning that features including cancers can appear later. That has direct consequences for relatives being tested.

Physical differences can bring surgeries and appointments that have nothing to do with blood counts. And adult life brings a different set of problems from childhood — iron management, hormone effects, and cancer surveillance starting with colonoscopy at 20.

For most children with Diamond-Blackfan anemia the first look is inside the family. The 2024 consensus puts a matched sibling first, then a fully matched unrelated donor, with half-matched or mismatched donors reserved for when there is no alternative.

But “usually a family donor” is not “always”. An unrelated donor is needed when there is no matched sibling — and, crucially, when the only matched sibling turns out to carry the family’s gene change.

That constraint is the most important thing on this page, and it is not widely known. A sibling with entirely normal blood counts can still carry the variant, and marrow from them may fail or never engraft at all. There is a published case of persistent red cell failure after a transplant from a sibling donor whose own Diamond-Blackfan anemia had not been diagnosed. So sibling donors must be tested for the specific variant found in the patient, even when they are completely well.

Because most cases arise new in the child rather than being inherited, most siblings will be unaffected. That is a probability, not a clearance. Testing is what clears a sibling donor; the absence of symptoms is not.

Timing shapes the search. The consensus recommends transplant before age ten in chronically transfused children, preferably at pre-school age, to limit toxicity — so this is a childhood-timed donor search rather than one that can be left.