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.

CDA type IV is characterized by mild to moderate splenomegaly. Hemoglobin is very low and patients are transfusion dependent. MCV is normal or mildly elevated. Erythropoiesis is normoblastic or mildly to moderately megaloblastic. Nonspecific erythroblast dysplasia is present.

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

Hereditary spherocytosis (also known as Minkowski–Chauffard syndrome) abnormality of erythrocytes. The disorder is caused by mutations in genes relating to membrane proteins that allow for the erythrocytes to change shape. The abnormal erythrocytes are sphere-shaped (spherocytosis) rather than the normal biconcave disk shaped. Dysfunctional membrane proteins interfere with the cell's ability to be flexible to travel from the arteries to the smaller capillaries. This difference in shape also makes the red blood cells more prone to rupture. Cells with these dysfunctional proteins are taken for degradation at the spleen. This shortage of erythrocytes results in hemolytic anemia.

It was first described in 1871 and is the most common cause of inherited hemolysis in Europe and North America within the Caucasian population, with an incidence of 1 in 5000 births. The clinical severity of HS varies from symptom-free

carrier to severe haemolysis because the disorder exhibits incomplete penetrance in its expression.

Symptoms include anemia, jaundice, splenomegaly, and fatigue. On a blood smear, Howell-Jolly bodies may be seen within red blood cells. Primary treatment for patients with symptomatic HS has been total splenectomy, which eliminates the hemolytic process, allowing normal hemoglobin, reticulocyte and bilirubin levels.

As in non-hereditary spherocytosis, the spleen destroys the spherocytes. This process of red blood cells rupturing directly results in varying degrees of anemia (causing a pale appearance and fatigue), high levels of bilirubin in the blood (causing jaundice), and splenomegaly.

Acute cases can threaten to cause hypoxia through anemia and acute kernicterus through high blood levels of bilirubin, particularly in newborns. Most cases can be detected soon after birth. An adult with this disease should have their children tested, although the presence of the disease in children is usually noticed soon after birth. Occasionally, the disease will go unnoticed until the child is about 4 or 5 years of age. A person may also be a carrier of the disease and show no signs or symptoms of the disease. Other symptoms may include abdominal pain that could lead to the removal of the spleen and/or gallbladder.

Chronic symptoms include anemia, increased blood viscosity, and splenomegaly, and some symptoms are still unknown at this stage. Furthermore, the detritus of the broken-down blood cells – unconjugated or indirect bilirubin – accumulates in the gallbladder, and can cause pigmented gallstones to develop. In chronic patients, an infection or other illness can cause an increase in the destruction of red blood cells, resulting in the appearance of acute symptoms, a "hemolytic crisis". Spherocytosis patients who are heterozygous for a hemochromatosis gene may suffer from iron overload despite the hemochromatosis genes being recessive.

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 (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.

Congenital dyserythropoietic anemia type IV (CDA IV) has been described with typical morphologic features of CDA II but a negative acidified-serum test.

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 signs and symptoms of CDA type III tend to be milder than those of the other types. Most affected individuals do not have hepatosplenomegaly, and iron does not build up in tissues and organs. In adulthood, abnormalities of a specialized tissue at the back of the eye (the retina) can cause vision impairment. Some people with CDA type III also have a blood disorder known as monoclonal gammopathy, which can lead to a cancer of white blood cells (multiple myeloma).

In a peripheral blood smear, the red blood cells will "appear" abnormally small and lack the central pale area that is present in normal red blood cells. These changes are also seen in non-hereditary spherocytosis, but they are typically more pronounced in hereditary spherocytosis. The number of immature red blood cells (reticulocyte count) will be elevated. An increase in the mean corpuscular hemoglobin concentration is also consistent with hereditary spherocytosis.

Other protein deficiencies cause hereditary elliptocytosis, pyropoikilocytosis or stomatocytosis.

In longstanding cases and in patients who have taken iron supplementation or received numerous blood transfusions, iron overload may be a significant problem. This is a potential cause of heart muscle damage and liver disease. Measuring iron stores is therefore considered part of the diagnostic approach to hereditary spherocytosis.

An osmotic fragility test can aid in the diagnosis. In this test, the spherocytes will rupture in liquid solutions less concentrated than the inside of the red blood cell. This is due to increased permeability of the spherocyte membrane to salt and water, which enters the concentrated inner environment of the RBC and leads to its rupture. Although the osmotic fragility test is widely considered the gold standard for diagnosing hereditary spherocytosis, it misses as many as 25% of cases. Flow cytometric analysis of eosin-5′-maleimide-labeled intact red blood cells and the acidified glycerol lysis test are two additional options to aid diagnosis.

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.

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".

1- Secondary anaemias

- Chronic infection/inflammation

- Malignancy

2- Thalassaemia

3- Sideroblastic anaemia

1- Red cell indices and blood film appearances suggest iron deficiency, although peripheral blood changes are not usually as marked as in moderate or severe iron deficiency.

2- Erythropoiesis is abnormal because of ineffective iron utilisation with poor haemoglobinisation of red cell precursors and

3- Bone marrow iron stores are normal or increased and sideroblasts may be frequent and abnormal.

Anemia goes undetected in many people and symptoms can be minor. The symptoms can be related to an underlying cause or the anemia itself.

Most commonly, people with anemia report feelings of weakness or tired, and sometimes poor concentration. They may also report shortness of breath on exertion. In very severe anemia, the body may compensate for the lack of oxygen-carrying capability of the blood by increasing cardiac output. The patient may have symptoms related to this, such as palpitations, angina (if pre-existing heart disease is present), intermittent claudication of the legs, and symptoms of heart failure.

On examination, the signs exhibited may include pallor (pale skin, lining mucosa, conjunctiva and nail beds), but this is not a reliable sign. There may be signs of specific causes of anemia, e.g., koilonychia (in iron deficiency), jaundice (when anemia results from abnormal break down of red blood cells — in hemolytic anemia), bone deformities (found in thalassemia major) or leg ulcers (seen in sickle-cell disease).

In severe anemia, there may be signs of a hyperdynamic circulation: tachycardia (a fast heart rate), bounding pulse, flow murmurs, and cardiac ventricular hypertrophy (enlargement). There may be signs of heart failure.

Pica, the consumption of non-food items such as ice, but also paper, wax, or grass, and even hair or dirt, may be a symptom of iron deficiency, although it occurs often in those who have normal levels of hemoglobin.

Chronic anemia may result in behavioral disturbances in children as a direct result of impaired neurological development in infants, and reduced academic performance in children of school age. Restless legs syndrome is more common in those with iron-deficiency anemia.

Hemoglobinopathy is a kind of genetic defect that results in abnormal structure of one of the globin chains of the hemoglobin molecule. Hemoglobinopathies are inherited single-gene disorders; in most cases, they are inherited as autosomal co-dominant traits. Common hemoglobinopathies include sickle-cell disease. It is estimated that 7% of world's population (420 million) are carriers, with 60% of total and 70% pathological being in Africa. Hemoglobinopathies are most common in populations from Africa, the Mediterranean basin and Southeast Asia.

Hemoglobinopathies imply structural abnormalities in the globin proteins themselves. Thalassemias, in contrast, usually result in underproduction of normal globin proteins, often through mutations in regulatory genes. The two conditions may overlap, however, since some conditions which cause abnormalities in globin proteins (hemoglobinopathy) also affect their production (thalassemia). Thus, some hemoglobinopathies are also thalassemias, but most are not.

Either hemoglobinopathy or thalassemia, or both, may cause anemia. Some well-known hemoglobin variants such as sickle-cell anemia and congenital dyserythropoietic anemia are responsible for diseases, and are considered hemoglobinopathies. However, many hemoglobin variants do not cause pathology or anemia, and thus are often not classed as hemoglobinopathies, because they are not considered pathologies. Hemoglobin variants are a part of the normal embryonic and fetal development, but may also be pathologic mutant forms of hemoglobin in a population, caused by variations in genetics. Other variants cause no detectable pathology, and are thus considered non-pathological variants.

Congenital dyserythropoietic anemia type III (CDA III) is a rare autosomal dominant disorder characterized by macrocytic anemia, bone marrow erythroid hyperplasia and giant multinucleate erythroblasts. New evidence suggests that this may be passed on recessively as well.

Pearson syndrome is a mitochondrial disease characterized by sideroblastic anemia and exocrine pancreas dysfunction. Other clinical features are failure to thrive, pancreatic fibrosis with insulin-dependent diabetes and exocrine pancreatic deficiency, muscle and neurologic impairment, and, frequently, early death. It is usually fatal in infancy. The few patients who survive into adulthood often develop symptoms of Kearns-Sayre syndrome.

It is caused by a deletion in mitochondrial DNA. Pearson syndrome is very rare, less than hundred cases have been reported in medical literature worldwide.

The syndrome was first described by pediatric hematologist and oncologist Howard Pearson in 1979; the deletions causing it were discovered a decade later.

A dimorphic appearance on a peripheral blood smear occurs when there are two simultaneous populations of red blood cells, typically of different size and hemoglobin content (this last feature affecting the color of the red blood cell on a stained peripheral blood smear). For example, a person recently transfused for iron deficiency would have small, pale, iron deficient red blood cells (RBCs) and the donor RBCs of normal size and color. Similarly, a person transfused for severe folate or vitamin B12 deficiency would have two cell populations, but, in this case, the patient's RBCs would be larger and paler than the donor's RBCs. A person with sideroblastic anemia (a defect in heme synthesis, commonly caused by alcoholism, but also drugs/toxins, nutritional deficiencies, a few acquired and rare congenital diseases) can have a dimorphic smear from the sideroblastic anemia alone. Evidence for multiple causes appears with an elevated RBC distribution width (RDW), indicating a wider-than-normal range of red cell sizes, also seen in common nutritional anemia.

Erythropoietic porphyria is a type of porphyria associated with erythropoietic cells. In erythropoietic porphyrias, the enzyme deficiency occurs in the red blood cells.

There are three types:

X-linked sideroblastic anemia or "X-linked dominant erythropoietic protoporphyria", associated with ALAS2 (aminolevulinic acid synthase), has also been described. X-linked dominant erythropoietic protoporphyria (XDEPP) is caused by a gain of function mutation in the ALAS2 (5-aminolevulinate synthase) gene; that gene encodes the very first enzyme in the heme biosynthetic pathway. The mutation is caused by a frameshift mutation caused by one of two deletions in the ALAS2 exon 11, either c. 1706-1709 delAGTG or c. 1699-1700 delAT. This alters the 19 and 20 residues of the C-terminal domain thereby altering the secondary structure of the enzyme. The delAT mutation only occurred in one family studied whereas the delAGTG mutation occurred in several genetically distinct families. The delAGTG causes a loss of an α-helix which is replaced by a β-sheet.

Previously known mutations in the ALAS2 resulted in a loss-of-function mutation causing X-linked sideroblastic anemia. Erythropoietic protoporphyria (EPP) has similar symptoms as X-linked dominant erythropoietic protoporphyria but the mutation occurs as a loss-of-function in the FECH (ferrochelatase) enzyme; the very last enzyme in the pathway. All individuals studied presented symptoms without mutations in the FECH enzyme. The patterns of inheritance led the researchers to conclude the mutation must come from an enzyme on the X-chromosome with ALAS2 being the most likely candidate.

X-linked dominant erythropoietic protoporphyria is distinct from EPP in that there is no overload of Fe ions. Additionally, unlike the other condition the arises out of a mutation of the ALAS2 gene, there is no anaemia. XDEPP is characterized by a buildup of protoporphyrin IX caused by in increased level of function in the ALAS2 enzyme. Because there is a buildup of protoporphyrin IX with no malfunction of the FECH enzyme, all the available Fe is used in the production of heme, causing the FECH enzyme to use Zn in its place, causing a buildup of zinc-protoporphyrin IX.

X-linked dominant erythropoietic protoporphyria is a relatively mild version of porphyria with the predominant symptom being extreme photosensitivity causing severe itching and burning sensation of the skin due to the buildup of protoporphyrin IX. One possible treatment was discovered when treating an individual with supplemental iron for a gastric ulcer. Levels of free protoporphyrin decreased significantly as there was iron available for the FECH to produce heme. Levels of zinc-protoporphyrin, however did not decrease.

The presentation of this disorder entails anemia, arthritis, hepatic anomalies, and recurrent infections are clinical signs of the disease. Iron overload occurs mainly in the liver, heart, pancreas, thyroid, and kidney

Atransferrinemia, also called familial hypotransferrinemia, is an autosomal recessive metabolic disorder in which there is an absence of transferrin, a plasma protein that transports iron through the blood.

Atransferrinemia is characterized by anemia and hemosiderosis in the heart and liver. The iron damage to the heart can lead to heart failure. The anemia is typically microcytic and hypochromic (the red blood cells are abnormally small and pale). Atransferrinemia was first described in 1961 and is extremely rare, with only ten documented cases worldwide.

Kostmann syndrome is a group of diseases that affect myelopoiesis, causing a congenital form of neutropenia (severe congenital neutropenia [SCN]), usually without other physical malformations. SCN manifests in infancy with life-threatening bacterial infections.

Most cases of SCN respond to treatment with granulocyte colony-stimulating factor (filgrastim), which increases the neutrophil count and decreases the severity and frequency of infections. Although this treatment has significantly improved survival, people with SCN are at risk of long-term complications such as hematopoietic clonal disorders (myelodysplastic syndrome, acute myeloid leukemia).

Kostmann disease (SCN3), the initial subtype recognized, was clinically described in 1956. This type has an autosomal recessive inheritance pattern, whereas the most common subtype of Kostmann syndrome, SCN1, shows autosomal dominant inheritance.

1. Blood. With Pearson Syndrome, the bone marrow fails to produce white blood cells called neutrophils. The syndrome also leads to anemia, low platelet count, and aplastic anemia It may be confused with transient erythroblastopenia of childhood.

2. Pancreas. Pearson Syndrome causes the exocrine pancreas to not function properly because of scarring and atrophy

Individuals with this condition have difficulty absorbing nutrients from their diet which leads to malabsorption. infants with this condition generally do not grow or gain weight.