Hemoglobinopathies Flashcards
ACOG
Hemoglobinopathies
Sickle cell involves a mutation of which Hbg type and side chain?
Hgb A, beta chain (glutamic acid -> valine)
Hemoglobinopathies
How common is sickle cell trait?
1/12 African Americans
Hemoglobinopathies
Aside from African Americans, who is at risk for carrying the sickle cell mutation? (ethnicity-wise)
Those from Greece, Italy, the Middle East, and East India
Hemoglobinopathies
What triggers RBCs to sickle in affected individuals?
Low O2 states
Hemoglobinopathies
Why are sickle cells bad - how do they cause harm?
Vasoocclusion of organs/tissues
Hemoglobinopathies
How does acute chest syndrome present?
Pulmonary infiltrates on CXR
Fever, hypoxia, acidosis
No infection
Hemoglobinopathies
What is the typical electrophoresis in sickle cell disease and trait?
SS: Mostly Hgb S, some A2 and F
Trait: Mostly Hgb A noted, with some S, A2, and F
Hemoglobinopathies
Who should be offered sickle cell carrier screening?
Those of African and mediterranean ancestry
Hemoglobinopathies
How should you screen for sickle cell in those with African or other heritage?
African-American: CBC + electrophoresis
Other: CBC with diff, and electrophoresis only if microcytic (<80)
Hemoglobinopathies
What are the risks associated with sickle cell disease in pregnancy?
PTL, PPROM, infection post-partum, IUGR, IUFD
Hemoglobinopathies
How much folic acid should patients with sickle cell take daily?
4mg/day
Hemoglobinopathies
How do you counsel patients with sickle cell on crisis avoidance?
Avoid triggers (cold, physical exertion, dehydration, and stress)
Hemoglobinopathies
Can hydroxyurea be used in pregnancy to avoid a sickle crisis?
No - hydroxyurea is teratogenic
Hemoglobinopathies
How do we treat sickle crises?
O2, opiods
Evaluation/treatment of cause (infection, dehydration)
Management of compliations (acute chest)
Hemoglobinopathies
When exchange transfusions are utilized in pregnancy for sickle cell, what is the typical indication?
Reduce frequency of pain crises
Hemoglobinopathies
With an exchange transfusion, what is the treatment goal for % HgbS?
Hgb S <40%
Hemoglobinopathies
How should we monitor fetuses in pregnancies complicated by SS?
Serial growth ultrasound q 4-6 weeks
Antepartum testing beginning at 32 weeks
Hemoglobinopathies
What electrophoresis pattern is consistent with beta-thalassemia?
Increased Hgb A2 > 3.5%, increased Hgb F, no Hgb S
Hemoglobinopathies
What causes B-thal?
Bad beta-chain -> loss of type A Hgb (alpha/beta)
Hemoglobinopathies
What are the two general types of gene mutations associated with B-thal?
B (0) - absent beta chain production
B (+) - decreased amount of beta chain production
Hemoglobinopathies
What are the two grades of B-thal severity?
B-thal MINOR: mild anemia
B-thal MAJOR: severe anemia, complications
Hemoglobinopathies
What complications are associated with B-thal major over a lifetime (outside of pregnancy)
Extramedullary hematopoeisis
Delayed sexual development (due to hemosiderin deposition in hypothalamus)
Poor growth
Death by age 10 if blood transfusions are not initiated
Hemoglobinopathies
What patients with B-thal major are candidates for pregnancy?
Normal heart function
No end organ damage from chronic transfusion (or h/o transfusion, coupled with deferoxamine for chelation)
Hemoglobinopathies
Which ethnicities are most commonly associated with B-thal mutations?
Mediterranean, Asian, middle eastern, Hispanic, W.Indian
Hemoglobinopathies
What is the outcome of B-thal combined with HgbS?
Severe anemia due to absent functional beta-chain production -> no Hgb A production
Hemoglobinopathies
While pregnancies with B-thal minor are usually favorable, what outcomes should be monitored for?
IUGR, oligohydramnios
Hemoglobinopathies
Instead of iron, what supplement should be given to women with B-thal?
Folic acid 1mg/day
Hemoglobinopathies
If you diagnose a patient with B-thal, what supplement should be initiated, and who else should be tested?
Initiated folic acid 1mg/day
Test father with CBC -> electrophoresis if microcytic
Genetic counseling if dad also a carrier
Hemoglobinopathies
When should you refer a patient for alpha-thal testing?
Microcytic anemia
Normal electrophoresis and iron testing
SE Asian, African, W Indian, and mediterranean
Hemoglobinopathies
What causese alpha-thalassemia?
Defunct alpha-chain production -> decreased Hgb A (alpha/beta), A2 (alpha/delta), and F (alpha/gamma)
Hemoglobinopathies
Alpha thall involves mutations in how many alpha genes? What are the possible mutation combinations called?
TRANS: a_/a_
CIS: __/aa
Hemoglobinopathies
What ethnicities are most likely to be affected by sickle cell?
SE Asian, African, W. Indian, Mediterranean
Hemoglobinopathies
Why are E.Asian individuals with a-thall more likely to have a child with Hgb Barts than African individuals?
CIS mutation (__/aa) seen more commonly in SE Asia -> more likely to have fetus with (__/__)
Hemoglobinopathies
What is the outcome of Hgb Barts?
Fetal hydrops, IUFD, preeclampsia
Hemoglobinopathies
Does a-thal worsen or improve sickle cell?
A-thal improves presentation of sickle cell, as less Hgb S (alpha/sickle) can be produced!)
