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79 Cards in this Set
- Front
- Back
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What does hemoglobinopathy meen?
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refers to a diseased state involving hemoglobin.
results from a genetic mutation in genes that affect hemoglobin synthesis |
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Qualitative hemoglobinopathy =
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when Hgb synthesis occurs at a normal rate but the Hgb molecule has an altered amino acid sequence in the globin chains.
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Quantitative hemoglobinopathy =
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reduced rate of Hgb synthesis but dont affect the amino acid sequence.
reduction in Hgb made |
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Structural defects hemoglobinopathy is qualitative or quantitative?
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qualitative
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Thalassemia is qualitative or quantitative?
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quatitative
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these two globin genes are on chromosome 16.
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a and 3
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these 4 globin genes are on chromosome 11.
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B, y, &, and E
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Gower 1 Hgb
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32 + E2
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Gower 2 Hgb
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a2 + E2
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Portland Hgb
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#2 + Y2
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at6 birth Hbg are?
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F, A
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Hgb A is made up of?
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A2 + B2
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How many structural hemoglobiopathies are there.
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>800
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Point mutation is the most common type of mutation and is the replacement of ?
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one original nucleotide with another.
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Deletions =
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removal of one or more nucleotides
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Insertions =
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addition of one more nucleotide
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Chain extensions =
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stop codon is mutated causing translation to continue on.
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Gene fusions =
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2 normal genes break between nucleotides and switch positions
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Impact of Hgb mutations on their function depends on?
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Type of amino acid substituted, location in the globin chain and number of genes mutated.
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Homozygous =
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more severe and more genes are mutated.
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Heterozygous =
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less severe and ussually only one gene is mutated.
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Most clinical abnormalities are associated with which chain?
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B
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what is the most severe abnormal Hgb?
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S
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4 classifications of Hgb.
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1. abnormal Hgb that result in hemolytic anemia
2. methemoglobinemia 3. Hgbs with increased or decreased oxygen affinity 4. abnormal Hgbs with no clinicalor functional affect. |
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Hgb S
1. has a trait that offers resistance against. 2. glumatic acid id replaced by? 3. is found most in these people? |
Plasmodium falciparum
Valine african decent, middle eastern, Indian, and Mediterrainian |
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the sickling process begins when oxygen saturation decreases to less than?
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85%
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in heterozygotes sickling begins at?
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<40%
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name the two types of sickle cells?
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reversible-change shape in response to the amount of oxygen carried.
irreversible-visible on blood smear. |
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The hallmark feature of Hgb S is?
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vaso-occlusion
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name some lab diagnostics of Hgb S?
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chronic hemolytic anemea.
sickle cells and target cells. marked anisocytosis.increased retics. insoluability in deoxyginated form. |
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what is the confirmatory test for Sickle cell anemia?
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Hemoglobin electrophoresis
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a sickle cell trait?
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refers to a heterozygous state, is a benign condition, asymptomatic, has normal RBC morphology, Hemoglobin solubility test is positive, diagnosed by detecting Hb S and Hg A on hemoglobin electrophoresis, 40% S and 60% A
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Hemglobin C?
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found almost exclusively in people of african decent.
short thick crystals within the RBC. marked increase in target cells and retics. negative hemoglobin solubility test. definitive diagnosis made with electrophoresis. |
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Hgb C-Harlem
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AKA Hgb C-Georgetown.
double substitution on the B chain.Termed this because of abnormal Hgb migrates with Hgb C on electrphoresis. Positive solubility test. electrophoresis needed to confirm. |
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Hemoglobin E
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SE asia (30% frequency).
amino substitution in B chain. Negative Hgb solubility test. |
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Hgb O-Arab`
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amino acid sub. in B chain.
rare disorder found in Kenya, Israel, Egypt, and bulgaria. many target cells. |
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Hgb D and Hgb G
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group of at least 16 B chain variations for Hgb D, and 6 a chain variations for Hgb G
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Doeble heterozygosity occurs when?
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inherit Hb S from one parent and another B chain hemoglobinopathy or thalassemia from the other parent
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Hgb SC
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most common double heterozygous syndrome.
resembles a mild SCD. Positive Hgb solubility test. in electrophoresis Hb C and Hb S migrate in equal amounts. |
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Hgb S/B-thalassemia
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resembles a mild or moderate sickle cell anemia.
greater amounts of Hb S than Hb A is how to tell this apart from sickle cell anemia. |
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Hgb M
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substitutions in the globin chains cause heme iron to oxydize from F2+ to F3+
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name Hgb with decreased oxygen affinity?
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Hb Kansas
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Thalassemias are caused by?
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gene alterations that decrease the rate of Hgb synthesis of one or more globin chains.
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Decreased globin production leads to?
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imbalanced globin chain synthesis.
Defective Hgb production. damage to red blood cells. |
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How are thalassemias named?
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according to the chain that has reduced or absent synthesis.
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Thalassemia belt?
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extends from the mediterranean east through the middle east, India to SE asia, and south through africa.
(seem to be present where there is more malaria) |
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2 theories of why thalassemia has resistence to malaria.
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defective growth of parasite in the affective cell or increase phagocytosis of the infective cells.
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thalassemia minor has Hgb of
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10-13 g/dl
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thalassemia intermedia has Hgb of
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7 g/dl
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thalassemia major has Hgb of
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3-4 g/dl
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The qualitative hemoglobinopathies cause disease by producing Hgb chains that are?
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structurally altered
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What hemoglobinopathy is most common?
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Sickle cell disease
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what clinical feature of sickle cell disease accounts for the highest number of hospital admissions?
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Vaso-oclusion
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Sickle cell disease is found in individuals decended from these places?
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Africa, Middle east,and the mediterrainian.
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Name 3 characteristics of sickle cell disease on a blood smear?
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target cells, Howell-Holly bodies, and leukocytosis
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name 3 characteristics in homozygous Hgb S?
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High retic count, Hgb A, and Hgb that is less soluable.
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A patient has target cells and a positive solubility test, this patient probably has?
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a sickle trait
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What is the test to best cofirm someone with a sickle trai?
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Hgb electrophoresis
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a patient has 45% Hgb S and 55% Hgb A and a positive solubility test, what would most likely be found on a blood smear?
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normal blood smear and no disease.
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If a patient has hereditary spherocytosis, would you find tartget cells?
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no
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Name 3 characteristics of a patient with Hgb SC disease or S/B - thalassemia?
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target cells, shortend red cell survival, and mild to moderate clinical features.
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Heinz bodies are found when Hgb?
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precipitates
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What is the correct relationship between red cells affinity for oxygen and red cell production?
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When affinity is high, less oxygen is released and the body compensates by increasing erythropoietin and making more red cells.
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What is the basic Hgb defect in the Thalassemias?
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a structurally normal globin chain is absent or produced at lower levels.
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What is the normal approximate percentage of Hgbs in adults?
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96% a2B2
2% a2&2 2% a2y2 |
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Why are infants with beta-thalassemia major not ill until about 6 months of age?
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infants are protected by their high concentration of fetal Hgb.
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What is the primary mechanism for anemia in the thalassemias?
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an inbalance in the rate of globin chain synthesis.`
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What is true regarding clinical features of thalassemias?
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they vary from benign forms to those incompatible with life.
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Would the presence of microcytosis, hypochromasia, and target cells distinguish thalassemia major from minor?
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no
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would normal fetal Hgb be expected or unexpected finding in homozygous beta-thalassemia?
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unexpected
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What finding is present in al types of alpha-thalassemias?
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barts Hgb present at birth.
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What is true of patients with Hgb H disease?
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have three missing genes for alpha chain production.
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Homozygous alpha-thalassemia (--/--) has what clinical outcome?
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incompatible with life.
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What is least usefull in diagnosing and differentiating the thalassemias from each other?
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osmotic fragility
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Hgb Bart is composed of?
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y4
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Iron overload in severe beta-thalassemia (major) patients is primarily a consequence of?
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accumulation of iron from massive red blood cell transfusions.
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Patients who are heterozygous for Hgb Lepore have a clinical course?
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similar to that of beta-thalassemia minor.
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Hgb E is primarily found in individuala of what ethnic origen?
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southeast asia
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Hemoglobin A2 and F can be quantified by?
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performing a high-performance liquid chromatography.
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