Diamond-Blackfan anemia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Diamond-Blackfan anemia is a disorder that primarily affects the bone marrow. People with this condition often also have physical abnormalities affecting various parts of the body.

The major function of bone marrow is to produce new blood cells. In Diamond-Blackfan anemia, the bone marrow malfunctions and fails to make enough red blood cells, which carry oxygen to the body's tissues. The resulting shortage of red blood cells (anemia) usually becomes apparent during the first year of life. Symptoms of anemia include fatigue, weakness, and an abnormally pale appearance (pallor).

People with Diamond-Blackfan anemia have an increased risk of several serious complications related to their malfunctioning bone marrow. Specifically, they have a higher-than-average chance of developing myelodysplastic syndrome (MDS), which is a disorder in which immature blood cells fail to develop normally. Individuals with Diamond-Blackfan anemia also have an increased risk of developing a bone marrow cancer known as acute myeloid leukemia (AML), a type of bone cancer called osteosarcoma, and other cancers.

Approximately half of individuals with Diamond-Blackfan anemia have physical abnormalities. They may have an unusually small head size (microcephaly) and a low frontal hairline, along with distinctive facial features such as wide-set eyes (hypertelorism); droopy eyelids (ptosis); a broad, flat bridge of the nose; small, low-set ears; and a small lower jaw (micrognathia). Affected individuals may also have an opening in the roof of the mouth (cleft palate) with or without a split in the upper lip (cleft lip). They may have a short, webbed neck; shoulder blades that are smaller and higher than usual; and abnormalities of their hands, most commonly malformed or absent thumbs. About one-third of affected individuals have slow growth leading to short stature.

Other features of Diamond-Blackfan anemia may include eye problems such as clouding of the lens of the eyes (cataracts), increased pressure in the eyes (glaucoma), or eyes that do not look in the same direction (strabismus). Affected individuals may also have kidney abnormalities; structural defects of the heart; and, in males, the opening of the urethra on the underside of the penis (hypospadias).

The severity of Diamond-Blackfan anemia may vary, even within the same family. Increasingly, individuals with "non-classical" Diamond-Blackfan anemia have been identified. This form of the disorder typically has less severe symptoms. For example, some affected individuals have mild anemia beginning later in childhood or in adulthood, while others have some of the physical features but no bone marrow problems.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Diamond-Blackfan anemia can be caused by mutations in one of many genes, including the RPL5, RPL11, RPL35A, RPS10, RPS17, RPS19, RPS24, and RPS26 genes. These and other genes associated with Diamond-Blackfan anemia provide instructions for making ribosomal proteins, which are components of cellular structures called ribosomes. Ribosomes process the cell's genetic instructions to create proteins.

Each ribosome is made up of two parts (subunits) called the large and small subunits. The ribosomal proteins produced from the RPL5, RPL11, and RPL35A genes are among those found in the large subunit. The proteins produced from the RPS10, RPS17, RPS19, RPS24, and RPS26 genes are among those found in the small subunit.

Some ribosomal proteins are involved in the assembly or stability of ribosomes. Others help carry out the ribosome's main function of building new proteins. Studies suggest that some ribosomal proteins may have other functions, such as participating in chemical signaling pathways within the cell, regulating cell division, and controlling the self-destruction of cells (apoptosis).

Approximately 25 percent of individuals with Diamond-Blackfan anemia have mutations in the RPS19 gene. About another 25 to 35 percent of individuals with this disorder have mutations in the RPL5, RPL11, RPL35A, RPS10, RPS17, RPS24, or RPS26 gene. Mutations in any of these genes are believed to cause problems with ribosome function. Studies indicate that a shortage of functioning ribosomes may increase the self-destruction of blood-forming cells in the bone marrow, resulting in anemia. Abnormal regulation of cell division or inappropriate triggering of apoptosis may contribute to the other health problems that affect some people with Diamond-Blackfan anemia. Scientists are working to determine why the blood abnormalities and physical problems can vary so much between individuals.

Mutations in many other genes, some of which have not been identified, account for the remaining Diamond-Blackfan anemia cases. While mutations in genes that provide instructions for ribosomal proteins cause most cases of Diamond-Blackfan anemia, gene changes affecting proteins that interact with ribosomal proteins or that play other roles in blood-forming processes have been identified in a few individuals with this disorder.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In approximately 45 percent of cases, an affected person inherits the mutation from one affected parent. The remaining cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Diamond-Blackfan anemia affects approximately 5 to 7 per million newborn babies worldwide.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Elevated red cell adenosine deaminase activity · Very frequent (99-80%)

Increase in the level of adenosine deaminase (ADA), an enzyme involved in purine metabolism, within erythrocytes. ADA is involved in the catabolism of adenosine.

Pure red cell aplasia · Very frequent (99-80%)

A type of anemia resulting from suppression of erythropoiesis with little or no abnormality of leukocyte or platelet production. Erythroblasts are virtually absent in bone marrow; however, leukocyte and platelet production show little or no reduction.

Abnormality of the head · Frequent (79-30%)

An abnormality of the head.

Erythroid hypoplasia · Frequent (79-30%)

Decreased count of erythroid precursor cells, that is, erythroid lineage cells in the bone marrow.

Growth delay · Frequent (79-30%)

A deficiency or slowing down of growth pre- and postnatally.

Increased mean corpuscular volume · Frequent (79-30%)

Larger than normal size of erythrocytes.

Lethargy · Frequent (79-30%)

A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks.

Pallor · Frequent (79-30%)

Abnormally pale skin.

Other findings in the same source

From: Orphanet

Additional reported features include Persistence of hemoglobin F (Frequent (79-30%)); Reticulocytopenia (Frequent (79-30%)); Small for gestational age (Frequent (79-30%)); Macrocytic dyserythropoietic anemia (Frequent (79-30%)); Abnormal heart morphology (Occasional (29-5%)); Abnormality of the genitourinary system (Occasional (29-5%)); Abnormality of the thenar eminence (Occasional (29-5%)); Abnormality of the upper limb (Occasional (29-5%)); Absent thumb (Occasional (29-5%)); Atrial septal defect (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Diamond-Blackfan anemia is Haematology, with a haematologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which blood-cell, marrow, bleeding or clotting finding matters most?
• Does the diagnosis need confirmation or a more precise subtype?
• Which symptoms or laboratory changes should trigger earlier review?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Diamond-Blackfan anemia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.