Studied by 18 people
mama mo mukhang sickle cell
Hemoglobinopathies
Results from a genetic mutation in one or more genes that affect hemoglobin synthesis
Qualitative Hemoglobinopathies
The hemoglobin molecule has an altered amino acid sequence within the globin chains
Quantitative Hemoglobinopathies
Thalassemias result in a reduced rate of hemoglobin synthesis but do not affect the amino acid sequence of the affected globin chains.
Point Mutation
The most common type of genetic mutation
Replacement of one original nucleotide in the normal gene with a different nucleotide.
Gene fusions
Occurs when two normal genes break between nucleotides, switch positions, and anneal to the opposite gene
Zygosity
Refers to the association between the number of gene mutations and the level of severity of the resultant genetic defect
Sickle Cell Disease (SCD)
This is the most common form of hemoglobinopathy
Hb S
Type of Hb in which sickling occurs when a solution of RBCs is deficient in oxygen.
Resistant against infection with P. falciparum
Reversible Sickle Cells
RBCs that change shape in response to oxygen tension.
Circulate as normal biconcave disc.
Able to travel into the microvasculature.
Irreversible Sickle Cells
RBCs do not change their shape.
Seen as elongated sickle cells with a point at each end.
Recognized as abnormal by the spleen and removed from circulation
Hemoglobin solubility test
The most common screening test for Hb S.
Alkaline hemoglobin electrophoresis
Based on the separation of hemoglobin molecules in an electric field, the result of differences in total molecular charge
High-Performance Liquid Chromatography (HPLC)
Used to confirm hemoglobin variants.
More automated
Separates hemoglobin types in a cation exchange columns
Best used in the diagnosis of thalassemia.
Capillary Electrophoresis
Separates hemoglobin types based on charge in an alkaline buffer
Use smaller volumes and produce better separation than traditional agarose electrophoresis
Isoelectric focusing
It is a confirmatory technique that is expensive and complex, requiring well-trained and experienced laboratory personnel
Hb C-Harlem
Type of Hb that has a Double - Substitution on the Beta Chain.
The substitution of valine for glutamic acid at position 6 of the beta chain and the substitution at position 73 of aspartic acid for asparagine
Hb S-β-Thalassemia
Type of Hb that resembles mild or moderate SCD
Hb S-Korle Bu
It is a rare hemoglobin variant with substitution of aspartic acid for asparagine at position 73 of the b chain
Hb M
The mutation in the Alpha, Beta, and Gamma Globin Genes results in the production of this Hb.
It also causes blood specimens to appear brown
Cyanosis
This is produced when iron in the ferric state is unable to carry oxygen.
Hb Köln
This is the most prevalent unstable hemoglobin
Plasmodium falciparum
This parasite is most associated with SCD
Vasoocclusive crisis
This is the hallmark of SCD
Spleen sequestration
This is characterized by a sudden trapping of blood in the spleen, which leads to a rapid decline in hemoglobin
Autosplenectomy
Gradual loss of splenic function is referred to as?
Fat embolism syndrome (FES)
A rare but often fatal sequalae of SCD
Aplastic episodes
The most common life-threatening hematologic complications and are usually associated with infection, particularly parvovirus infection
Megaloblastic episodes
These episodes result from the sudden arrest of erythropoiesis caused by folate depletion
Avascular necrosis (AVN)
Impaired blood supply to the head of the femur and humerus results in a condition called
Hand-foot syndrome
This is characterized by pain and swelling in the hands and feet of children younger than 3 years
Hb C
Type of Hb that is found primarily in people of African descent
Decreased production of a globin chain
REVIEW QUESTION:
A qualitative abnormality in hemoglobin may involve all of the following except:
Polymerizes to form tactoid crystals
REVIEW QUESTION:
The substitution of valine for glutamic acid at position 6 of the b chain of hemoglobin results in hemoglobin that:
Higher levels of Hb F are present
GUIDE QUESTIONS:
Patients with SCD usually do not exhibit symptoms until 6 months of age because:
Folic acid
Megaloblastic episodes in SCD can be prevented by prophylactic administration of:
Hemoglobin electrophoresis at acid pH
Which of the following is the most definitive test for Hb S?
Substitution of lysine for glutamic acid at position 6 of the b chain
REVIEW QUESTION:
A patient presents with mild normochromic, normocytic anemia. On the peripheral blood film, there are a few target cells, rare nucleated RBCs, and hexagonal crystals within and lying outside of the RBCs. Which abnormality in the hemoglobin molecule is most likely?
The patient has Hb M.
REVIEW QUESTION:
A well-mixed specimen obtained for a CBC has a brown color. The patient is being treated with a sulfonamide for a bladder infection. Which of the following could explain the brown color?
25%
REVIEW QUESTION:
Through routine screening, prospective parents discover that they are both heterozygous for Hb S. What percentage of their children potentially could have sickle cell anemia (Hb SS)?
Vasoocclusion
REVIEW QUESTION:
Painful crises in patients with SCD occur as a result of:
Are insoluble in reduced, deoxygenated form
REVIEW QUESTION:
The screening test for Hb S that uses a reducing agent, such as sodium dithionite, is based on the fact that hemoglobins that sickle:
Homozygous/disease
REVIEW QUESTION:
DNA analysis documents a patient has inherited the sickle mutation in both b-globin genes. The two terms that best describe this genotype are:
Sub-Saharan Africa
REVIEW QUESTION:
In which of the following geographic areas is Hb S most prevalent?
Hb E
REVIEW QUESTION:
Which hemoglobinopathy is more common in Southeast Asian patients?
Hb SG
REVIEW QUESTION:
Which of the following Hb S compound heterozygotes exhibits the mildest symptoms?
Only homozygotes are symptomatic
REVIEW QUESTION:
Unstable hemoglobins exhibit all of the following findings except:
Note 
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