Symptoms of sideroblastic anemia include skin paleness, fatigue, dizziness, and enlarged spleen and liver. Heart disease, liver damage, and kidney failure can result from iron buildup in these organs.

Diamond–Blackfan anemia is characterized by normocytic or macrocytic anemia (low red blood cell counts) with decreased erythroid progenitor cells in the bone marrow. This usually develops during the neonatal period. About 47% of affected individuals also have a variety of congenital abnormalities, including craniofacial malformations, thumb or upper limb abnormalities, cardiac defects, urogenital malformations, and cleft palate. Low birth weight and generalized growth delay are sometimes observed. DBA patients have a modest risk of developing leukemia and other malignancies.

Sideroblastic anemia is typically divided into subtypes based on its cause.

- Hereditary or congenital sideroblastic anemia may be X-linked or autosomal.

GLRX5 has also been implicated.

- Acquired, or secondary, sideroblastic anemia develops after birth and is divided according to its cause.

The symptoms and signs of congenital dyserythropoietic anemia are consistent with:

- Tiredness (fatigue)

- Weakness

- Pale skin

Anemia may lead to malaise, pallor and associated symptoms such as palpitations.

Low platelet counts (thrombocytopenia) if present is associated with an increased risk of hemorrhage, bruising and petechiae. Low white blood cell counts (leukocytopenia) if present leads to an increased risk of infections which can be severe.

Symptoms can be extremely varied among those suffering from pyruvate kinase deficiency. The majority of those suffering from the disease are detected at birth while some only present symptoms during times of great physiological stress such as pregnancy, or with acute illnesses (viral disorders). Symptoms are limited to or most severe during childhood. Among the symptoms of pyruvate kinase deficiency are:

- Mild to severe hemolytic Anemia

- Cholecystolithiasis

- Tachycardia

- Hemochromatosis

- Icteric sclera

- Splenomegaly

- Leg ulcers

- Jaundice

- Fatigue

- Shortness of breath

Diamond–Blackfan anemia (DBA) is a congenital erythroid aplasia that usually presents in infancy. DBA causes low red blood cell counts (anemia), without substantially affecting the other blood components (the platelets and the white blood cells), which are usually normal. This is in contrast to Shwachman–Bodian–Diamond syndrome, in which the bone marrow defect results primarily in neutropenia, and Fanconi anemia, where all cell lines are affected resulting in pancytopenia.

A variety of other congenital abnormalities may also occur in DBA.

FA is characterized by bone marrow failure, AML, solid tumors, and developmental abnormalities. Classic features include abnormal thumbs, absent radii, short stature, skin hyperpigmentation, including café au lait spots, abnormal facial features (triangular face, microcephaly), abnormal kidneys, and decreased fertility. Many FA patients (about 30%) do not have any of the classic physical findings, but Diepoxybutane chromosome fragility assay showing increased chromosomal breaks can make the diagnosis. . About 80% of FA will develop bone marrow failure by age 20.

The first sign of a hematologic problem is usually petechiae and bruises, with later onset of pale appearance, feeling tired, and infections. Because macrocytosis usually precedes a low platelet count, patients with typical congenital anomalies associated with FA should be evaluated for an elevated red blood cell mean corpuscular volume.

Congenital hemolytic anemia (or hereditary hemolytic anemia) refers to hemolytic anemia which is primarily due to congenital disorders.

CDA may be transmitted by both parents autosomal recessively or dominantly and has over four different subtypes, but CDA Type I, CDA Type II, CDA Type III, and CDA Type IV are the most common. CDA type II (CDA II) is the most frequent type of congenital dyserythropoietic anemias. More than 300 cases have been described, but with the exception of a report by the International CDA II Registry, these reports include only small numbers of cases and no data on the lifetime evolution of the disease.

Congenital hypoplastic anemia (or constitutional aplastic anemia) is a type of aplastic anemia which is primarily due to a congenital disorder.

Associated genes include "TERC", "TERT", "IFNG", "NBS1", "PRF1", and "SBDS".

Examples include:

- Fanconi anemia

- Diamond-Blackfan anemia

Typical causes of microcytic anemia include:

- Childhood

- Iron deficiency anemia, by far the most common cause of anemia in general and of microcytic anemia in particular

- Thalassemia

- Adulthood

- Iron deficiency anemia

- Sideroblastic anemia, In congenital sideroblastic anemia the MCV (mean corpuscular volume) is either low or normal. In contrast, the MCV is usually high in the much more common acquired sideroblastic anemia.

- Anemia of chronic disease, although this more typically causes normochromic, normocytic anemia. Microcytic anemia has been discussed by Weng et al.

- Lead poisoning

- Vitamin B (pyridoxine) deficiency

Other causes that are typically thought of as causing normocytic anemia or macrocytic anemia must also be considered, and the presence of two or more causes of anemia can distort the typical picture.

There are five main causes of microcytic anemia forming the acronym TAILS. Thalassemia, Anemia of chronic disease, Iron deficiency, Lead poisoning and Congenital sideroblastic anemia. Only the first three are common in most parts of the world. In theory, these three can be differentiated by their red blood cell (RBC) morphologies. Anemia of chronic disease shows unremarkable RBCs, iron deficiency shows anisocytosis, anisochromia and elliptocytosis, and thalessemias demonstrate target cells and coarse basophilic stippling. In practice though elliptocytes and anisocytosis are often seen in thalessemia and target cells occasionally in iron deficiency. All three may show unremarkable RBC morphology. Coarse basophlic stippling is one reliable morphologic finding of thalessemia which does not appear in iron deficiency or anemia of chronic disease. The patient should be in an ethnically at risk group and the diagnosis is not confirmed without a confirmatory method such as hemoglobin HPLC, H body staining, molecular testing or another reliable method. Course basophlic stippling occurs in other cases as seen in Table 1

Microcytic anaemia is any of several types of anaemia characterized by small red blood cells (called microcytes). The normal mean corpuscular volume (abbreviated to MCV on full blood count results) is 80-100 fL, with smaller cells (100 fL) as macrocytic (the latter occur in macrocytic anemia).The MCV is the average red blood cell size.

In microcytic anaemia, the red blood cells (erythrocytes) are usually also hypochromic, meaning that the red blood cells appear paler than usual. This is reflected by a lower-than-normal mean corpuscular hemoglobin concentration (MCHC), a measure representing the amount of hemoglobin per unit volume of fluid inside the cell; normally about 320-360 g/L or 32-36 g/dL. Typically, therefore, anemia of this category is described as "microcytic, hypochromic anaemia".

Megaloblastic anemia (or megaloblastic anaemia) is an anemia (of macrocytic classification) that results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the G2 growth stage to the mitosis (M) stage. This leads to continuing cell growth without division, which presents as macrocytosis.

Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias.

The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically a deficiency of vitamin B and/or folic acid. Vitamin B deficiency alone will not cause the syndrome in the presence of sufficient folate, as the mechanism is loss of B dependent folate recycling, followed by folate-deficiency loss of nucleic acid synthesis (specifically thymine), leading to defects in DNA synthesis. Folic acid supplementation in the absence of vitamin B prevents this type of anemia (although other vitamin B-specific pathologies may be present). Loss of micronutrients may also be a cause. Copper deficiency resulting from an excess of zinc from unusually high oral consumption of zinc-containing denture-fixation creams has been found to be a cause.

Megaloblastic anemia not due to hypovitaminosis may be caused by antimetabolites that poison DNA production directly, such as some chemotherapeutic or antimicrobial agents (for example azathioprine or trimethoprim).

The pathological state of megaloblastosis is characterized by many large immature and dysfunctional red blood cells (megaloblasts) in the bone marrow and also by hypersegmented neutrophils (those exhibiting five or more nuclear lobes ("segments"), with up to four lobes being normal). These hypersegmented neutrophils can be detected in the peripheral blood (using a diagnostic smear of a blood sample).

The two most common signs and symptoms of bone marrow failure are bleeding and bruising. Blood may be seen throughout the gums, nose or the skin, and tend to last longer than normal. Children have a bigger chance of seeing blood in their urine or stools, which results in digestive problems with an unpleasant scent. Individuals with this condition may also encounter tooth loss or tooth decay. Chronic fatigue, shortness of breath, and recurrent colds can also be symptoms of bone marrow failure.

The blood film can point towards vitamin deficiency:

- Decreased red blood cell (RBC) count and hemoglobin levels

- Increased mean corpuscular volume (MCV, >100 fL) and mean corpuscular hemoglobin (MCH)

- Normal mean corpuscular hemoglobin concentration (MCHC, 32–36 g/dL)

- The reticulocyte count is decreased due to destruction of fragile and abnormal megaloblastic erythroid precursor.

- The platelet count may be reduced.

- Neutrophil granulocytes may show multisegmented nuclei ("senile neutrophil"). This is thought to be due to decreased production and a compensatory prolonged lifespan for circulating neutrophils, which increase numbers of nuclear segments with age.

- Anisocytosis (increased variation in RBC size) and poikilocytosis (abnormally shaped RBCs).

- Macrocytes (larger than normal RBCs) are present.

- Ovalocytes (oval-shaped RBCs) are present.

- Howell-Jolly bodies (chromosomal remnant) also present.

Blood chemistries will also show:

- An increased lactic acid dehydrogenase (LDH) level. The isozyme is LDH-2 which is typical of the serum and hematopoetic cells.

- Increased homocysteine and methylmalonic acid in Vitamin B deficiency

- Increased homocysteine in folate deficiency

Normal levels of both methylmalonic acid and total homocysteine rule out clinically significant cobalamin deficiency with virtual certainty.

Bone marrow (not normally checked in a patient suspected of megaloblastic anemia) shows megaloblastic hyperplasia.

In general, signs of anemia (pallor, fatigue, shortness of breath, and potential for heart failure) are present. In small children, failure to thrive may occur in any form of anemia. Certain aspects of the medical history can suggest a cause for hemolysis, such as drugs, consumption of fava beans due to Favism, the presence of prosthetic heart valve, or other medical illness.

Chronic hemolysis leads to an increased excretion of bilirubin into the biliary tract, which in turn may lead to gallstones. The continuous release of free hemoglobin has been linked with the development of pulmonary hypertension (increased pressure over the pulmonary artery); this, in turn, leads to episodes of syncope (fainting), chest pain, and progressive breathlessness. Pulmonary hypertension eventually causes right ventricular heart failure, the symptoms of which are peripheral edema (fluid accumulation in the skin of the legs) and ascites (fluid accumulation in the abdominal cavity).

Basically classified by causative mechanism, types of congenital hemolytic anemia include:

- Genetic conditions of RBC Membrane

- Hereditary spherocytosis

- Hereditary elliptocytosis

- Genetic conditions of RBC metabolism (enzyme defects). This group is sometimes called "congenital nonspherocytic (hemolytic) anemia", which is a term for a congenital hemolytic anemia without spherocytosis, and usually excluding hemoglobin abnormalities as well, but rather encompassing defects of glycolysis in the erythrocyte.

- Glucose-6-phosphate dehydrogenase deficiency (G6PD or favism)

- Pyruvate kinase deficiency

- Aldolase A deficiency

- Hemoglobinopathies/genetic conditions of hemoglobin

- Sickle cell anemia

- Congenital dyserythropoietic anemia

- Thalassemia

Aplastic anemia is a rare disease in which the bone marrow and the hematopoietic stem cells that reside there are damaged. This causes a deficiency of all three blood cell types (pancytopenia): red blood cells (anemia), white blood cells (leukopenia), and platelets (thrombocytopenia). "Aplastic" refers to inability of the stem cells to generate mature blood cells.

It is most prevalent in people in their teens and twenties, but is also common among the elderly. It can be caused by heredity, immune disease, or exposure to chemicals, drugs, or radiation. However, in about half the cases, the cause is unknown.

The definitive diagnosis is by bone marrow biopsy; normal bone marrow has 30–70% blood stem cells, but in aplastic anemia, these cells are mostly gone and replaced by fat.

First line treatment for aplastic anemia consists of immunosuppressive drugs, typically either anti-lymphocyte globulin or anti-thymocyte globulin, combined with corticosteroids and ciclosporin. Hematopoietic stem cell transplantation is also used, especially for patients under 30 years of age with a related matched marrow donor.

Fanconi anaemia (FA) is a rare genetic disease resulting in impaired response to DNA damage. Although it is a very rare disorder, study of this and other bone marrow failure syndromes has improved scientific understanding of the mechanisms of normal bone marrow function and development of cancer. Among those affected, the majority develops cancer, most often acute myelogenous leukemia, and 90% develop bone marrow failure (the inability to produce blood cells) by age 40. About 60–75% of people have congenital defects, commonly short stature, abnormalities of the skin, arms, head, eyes, kidneys, and ears, and developmental disabilities. Around 75% of people have some form of endocrine problems, with varying degrees of severity.

FA is the result of a genetic defect in a cluster of proteins responsible for DNA repair.

Treatment with androgens and hematopoietic (blood cell) growth factors can help bone marrow failure temporarily, but the long-term treatment is bone marrow transplant if a donor is available. Because of the genetic defect in DNA repair, cells from people with FA are sensitive to drugs that treat cancer by DNA crosslinking, such as mitomycin C. The typical age of death was 30 years in 2000.

FA occurs in about one per 130,000 births, with a higher frequency in Ashkenazi Jews in Israel and Afrikaners in South Africa. The disease is named after the Swiss pediatrician who originally described this disorder, Guido Fanconi. It should not be confused with Fanconi syndrome, a kidney disorder also named after Fanconi.

Hemolytic anemia or haemolytic anaemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular, but usually in the spleen). It has numerous possible consequences, ranging from relatively harmless to life-threatening. The general classification of hemolytic anemia is either inherited or acquired. Treatment depends on the cause and nature of the breakdown.

Symptoms of hemolytic anemia are similar to other forms of anemia (fatigue and shortness of breath), but in addition, the breakdown of red cells leads to jaundice and increases the risk of particular long-term complications, such as gallstones and pulmonary hypertension.

Pyruvate kinase deficiency is an inherited metabolic disorder of the enzyme pyruvate kinase which affects the survival of red blood cells. Both autosomal dominant and recessive inheritance have been observed with the disorder; classically, and more commonly, the inheritance is autosomal recessive. Pyruvate kinase deficiency is the second most common cause of enzyme-deficient hemolytic anemia, following G6PD deficiency.

Bone marrow failure in both children and adults can be either inherited or acquired. Inherited bone marrow failure is often the cause in young children, while older children and adults may acquire the disease later in life. A maturation defect in genes is a common cause of inherited bone marrow failure. The most common cause of acquired bone marrow failure is aplastic anemia. Working with chemicals such as benzene could be a factor in causing the illness. Other factors include radiation or chemotherapy treatments, and immune system problems.

Signs and symptoms are nonspecific and generally related to the blood cytopenias:

- Anemia (low RBC count or reduced hemoglobin) —chronic tiredness, shortness of breath, chilled sensation, sometimes chest pain

- Neutropenia (low neutrophil count) — increased susceptibility to infection

- Thrombocytopenia (low platelet count) — increased susceptibility to bleeding and ecchymosis (bruising), as well as subcutaneous hemorrhaging resulting in purpura or petechiae

Many individuals are asymptomatic, and blood cytopenia or other problems are identified as a part of a routine blood count:

- Neutropenia, anemia, and thrombocytopenia

- Splenomegaly or rarely hepatomegaly

- Abnormal granules in cells, abnormal nuclear shape and size

- Chromosome abnormality, including chromosomal translocations and abnormal chromosome number

Although some risk exists for developing acute myelogenous leukemia, about 50% of deaths occur as a result of bleeding or infection. However, leukemia that occurs as a result of myelodysplasia is notoriously resistant to treatment.

Anemia dominates the early course. Most symptomatic patients complain of the gradual onset of fatigue and weakness, dyspnea, and pallor, but at least half the patients are asymptomatic and their MDS is discovered only incidentally on routine blood counts. Previous chemotherapy or radiation exposure is an important fact in the person's medical history. Fever and weight loss should point to a myeloproliferative rather than myelodysplastic process.

Anemia of prematurity refers to a form of anemia affecting preterm infants with decreased hematocrit.