Dana Alsulaibi. - Ahmad Almuhtaseb. - Tariq Al - Adaily

Transcription

1 - 2 - Dana Alsulaibi - Ahmad Almuhtaseb - Tariq Al - Adaily

2 This sheet will talk about 4 diseases that cause hemolytic anemia, best of luck! 1) Hereditary Spherocytosis Transferred through inheritance Autosomal Dominant disease: A person affected by an autosomal dominant disorder has a 50 % chance of passing the mutated gene to each child Frameshift mutations RBCs shape like ball, instead of a biconcave disk hence are called spherocytes Intrinsic defects in the red cell membrane skeleton result in abnormalities in cell membrane proteins Common in Northern Europe, especially in Scandinavia. Not common in our region Spherocytes are smaller than normal rbcs yet have a normal heamoglobin concentration. Thus, MCHC is high and cells are hyperchromic, representing red balls Normal gas exchange and delivery of oxygen Mild symptoms Spherocytic RBC s are destroyed in the spleen. This is the main cause of anemia Abnormal osmatic fragility test Treatment: splenectomy Life span is reduced to 20 days instead of 120 days

3 PATHOGENESIS Mutation leads to absence or malfunction of one or more of cytoskeletal membrane proteins : band 3, band 4.2, ankyrin,,α spectrin, β spectrin Reduction in stability of the cell skeleton = fragmentation of rbc s membrane upon contact with other surfaces = rbc s become smaller eventually forming spherocytes CLINICAL FEATURES Congestion of RBCs in the spleen causes splenomegaly and anemia (extra vascular hemolytic anemia) Jaundice, pigmented gall bladder stones (Symptoms of extra vascular hemolytic anemia) Reticulocytosis (reticulocyte formation in the bone marrow is increased by erythropoietin) 75% of cases present with a family history of anemia or splenectomy, 25% are new mutations Abnormal osmotic fragility test: spherocytes lyse easier than normal rbc s. However, this is not specific only to this disease MORPHOLOGY Blood film: RBCs are round, small, hyperchromatic with no visible central pallor Howell-Jolly bodies are seen in post- splenectomy During maturation in the bone marrow, late erythroblasts normally expel their nuclei; but, in some cases, a small portion of DNA remains, secondary to accelerated erythropoiesis. Cells with residual DNA are normally removed by the spleen. However in patients who

4 have under gone splenectomy, these cells are not removed so the blood film show spherocytes and Howell jolly bodies (clusters of DNA that appear as 1 or 2 eccentric dots) spherocyte 2) Glucose-6-Phosphate Dehydrogenase Deficiency X linked disease (males are more affected than females) G6PD reduces nicotinamide adenine dinucleotide phosphate (NADP) to NADPH while oxidizing glucose-6- phosphate NADPH reduces oxidized glutathione reductase to reduced glutathione reductase, which is the enzyme that is responsible for keeping glutathione in its reduced form, Reduced glutathione reduces for example H2O2(hydrogen peroxide) to water.

5 Present in all cells, but its deficiency shows symptoms mainly on rbc s. Why? 1. RBCs have only one source to produce NADPH, while other cells have more than one source to produce NADPH (malic enzyme) 2.Plus, RBCs have a long life which subjects them to decreasing G6PD levels as cells age. Types of G6PD deficiency Several hundred G6PD genetic variants are known, but most are harmless The normal enzyme is called G6PD B Only two variants, designated G6PD A- and G6PD Mediterranean, cause most of the clinically significant hemolytic anemias.

6 G6PD A- is present in about 10% of American blacks; G6PD Mediterranean is prevalent in the Middle East. G6pd medit- is very common in our area Because mature red cells do not synthesize new proteins, G6PD-A or G6PD Mediterranean enzyme activities fall quickly to levels inadequate to protect against oxidant stress as red cells age. Thus, older red cells are much more prone to hemolysis than younger ones PATHOGENESIS The half-life of G6PD A- is moderately reduced, whereas that of G6PD Mediterranean is functionally abnormal. In G6PD A- the quantity of enzyme is reduced In G6PD Mediterranean, quantity is normal, functionality is reduced In patients with G6PD-A and G6PD-mediteranean, the bone marrow produces rbcs with below normal levels of G6PD. These rbcs function normally at first. However, Because of the long life of rbcs, as opposed to other nucleated cells in the body, G6PD levels drop as cells age. Problems arise when G6PD levels drop 20% below normal levels, and eventually become depleted. ROS increases and cells undergo lysis (FROM SLIDES) Because mature red cells do not synthesize new proteins(no nucleus), G6PD-A or G6PD Mediterranean enzyme activities fall quickly to levels inadequate to protect against oxidant stress as red cells age. Thus, older red cells are much more prone to hemolysis than younger ones.

7 Under exposure to high levels of oxidants, both intravascular and extravascular hemolysis occurs ROS cross-link globin chains, denaturing them. These denatured chains condense and form membrane bound precipitates called Heinz bodies that damage cell membrane supravital, crystal violet stain is used to view Heinz bodies. Rbcs stain yellow and Heinz bodies appear as green dots Splenic macrophages identify Heinz bodies and pluck them out bite cells. Rbc s appear as bitten cells just like the image below. Heinz bodies appear as green dots Bite cell

8 Causes of hemolytic crisis Infections: free radicals are excreted by neutrophils and macrophages Drugs: antimalarials (e.g., primaquine and chloroquine), sulfonamides, nitrofurantoin s *important, you have to take history from patient to check if they have anemia before administering these drugs. (التفو ل) (Favism) Food: fava bean Chemicals: Naphthalene, aniline dyes Unknown reason: chronic low-grade hemolytic anemia in neonates. This disease is an exception as hemolysis is persistent. Normally, G6PD deficiency presents as crisis from time to time. Other than that, patient functions normally. Clinical features Normally asymptomatic anemia develops when the enzyme level drops below 20% of normal activity Hemolytic crisis appear 2-3 days after exposure to oxidant(take history of patient till 3 days before hemolytic crisis) Only old RBCs hemolyze, hemoglobin level drops and RBCs appear normochromic normocytic with Heinz bodies Patients have Bone, muscle, joint pain because of hemolysis. Typically, splenomegaly and GB stones are absent G6PD A- usually is self-limited G6PD-Mediterranian has more severe crisis, might need blood transfusion.

9 Recovery is associated with reticulocytosis Dx: enzyme assay measure conversion to NAPDH diagnostic to both G6PD A- and Mediterranean. We do not measure G6PD levels as they will appear normal in Mediterranean variant. 3)Pyruvate kinase deficiency Rare disease PK is an enzyme in the anaerobic glycolysis pathway (main pathway in RBCs) PK deficiency causes decreased ATP level which is essential for cell membrane pumps (Na/K pump) Intracellular Na accumulates, causing swelling of RBCs and rigidity and eventually hemolysis. The Spleen clears abnormal shaped RBCs pyruvate kinase deficiency is less severe than G6PD deficiency as in PKD, 2,3 diphosphoglycerate (DPG) level increases inside RBCs, facilitating O2 release and thus lightening the anemia. CLINICAL - Degree of anemia varies according to type of mutation, ranging from neonatal jaundice to an adult with no symptoms - Anemia is exacerbated by stress, like physical exercise - Can present with jaundice, GB stones and splenomegaly -Blood film shows Normochromic Normocytic anemia with anisopoikilocytosis and variable reticulocytosis. * Anisopoikilocytosis: a medical condition illustrated by a variance in size (anisocytosis) and shape (poikilocytosis) of a red blood cell.

10 -Diagnosis: enzyme assay for pyruvate kinase -Treatment: splenectomy The previous diseases 1)hereditary spherocytosis 2) G6PD deficiency 3)pyruvate kinase deficiency >>>>ALL ARE HEREDITARY 4)Paroxysmal Nocturnal Hematuria Paroxysmal: sudden, nocturnal: at night, hematuria: blood in urine Acquired disease, mutation occurs later in life Pathogenesis Some proteins are attached to cell membrane through a covalent linkage to a specialized phospholipid called glycosylphosphatidylinositol (GPI), a cytoskeletal protein which gives stability and anchors others proteins In PNH, there is a mutation in the phosphatidylinositol glycan complementation group A gene (PIG-A), which synthesizes GPI Thus, GPI and their normally anchored proteins are absent Mutation occurs in hematopoietic stem cell, so GPI is absent in RBC s, WBC s and megakaryocytes (all lineage cells) CD55(decay accelerating factor) and CD59 (MIRL) are anchored to G6PD. They neutralize the complement system to protect healthy cells from being destroyed. In the absence of GPI: CD 55 AND CD59 cannot anchor to the cell membrane and protect it and cells undergo hemolysis. Thus,

11 paroxysmal nocturnal hematuria is characterized by ^intra vascular hemolysis. Consequences of deficiency: C3 convertase alternative pathway is activated Extra: The alternative pathway is one of three complement pathways that opsonize and kill pathogens PIG-A mutation among healthy people is frequent, meaning those people carry the mutation and yet are completely symptomless Explanation theory: Although some hematopoietic stem cells (HSCs) are mutated, other HSCs are healthy and compensate for the shortage. However, symptoms appear when an Autoimmune disease attacks normal cells, decreasing their number. So this disease is apparent in people with autoimmune diseases. CLINICAL FEATURES 1)Anemia Acute anemia: patients comes with sudden hematuria,25% nocturnal. We use ham test (a test to calculate heamogobin in urine) Chronic anemia: minor hemolysis persistent during day and night, low hematuria not as much as in acute PNH 2)Platelets (fatal): Thrombocytopenia with frequent thrombosis; Complement system lyses platelets, upon lysis, platelets release their contents and aggregate, leading to sudden thrombosis than can cause death

12 (notice that this an exception in PNH, where there is low platelet count, yet thrombosis occurs) 3)Granulocytes: Neutropenia ± In severe cases: pancytopenia which overlaps with aplastic anemia because of similar symptoms Due to mutation, PNH has a 5-10 % chance to develop into MDS (Myelodysplastic syndrome) OR AML (Acute myeloid leukemia) DIAGNOSIS: Flow cytometry (detection of CD55, CD59 on WBCs and RBCs) * this is the test used now, not ham test Lactate dehydrogenase: increased in all hemolytic anemias Retic count PNH is a rare and difficult disease to diagnose, as cells have normal morphology. Patient might also present with unexplained thrombosis. So, you have to put PTH in the bottom of the list of diseases you have to check for. Index: ~~ End of sheet ~~ Intravascular hemolysis: rupture or lysis of RBC within the circulation Pancytopenia: deficiency of all three cellular components of the blood (red cells, white cells, and platelets). Myelodysplastic syndromes (MDS) :a group of cancers in which immature blood cells in the bone marrow do not mature and therefore do not become healthy blood cells