Genetic Counseling Boards (Exam questions with 100% correct answers)

*Sickle Cell* Genetics Phenotype Diagnosis Treatment correct answers *Genetics:* HbSS Gluexon6Val mutation in HBB gene chr. 11p15.4 *Phenotype:* Structurally abnormal Hb Manifests at 6-12 months (HbF --> HbA) Painful crises, anemia, organ damage, pulmonary HTN *Diagnosis:* Hb electrophoresis *Treatment:* hydroxyurea (stimulates HbF) *Alpha-thalassemia* Genetics Phenotype correct answers *Genetics:* 2 alpha globin genes (4 alleles) chr. 16 *Phenotype:* aa/ao = silent carrier alpha-thal Heme healthy, occasionally low RBC indices ao/ao, aa/oo = alpha-thal trait mild anemia, low RBC indices oo/ao = HbH (B-chain tetramers --> "Heinz bodies" mild to moderately severe anemia, splenomegaly, icterus, abnormal RBC indices oo/oo = alpha-thal major severe, hydrops fetalis, incompat. with life *B-thalassemia* Genetics Phenotype correct answers *Genetics:* B-globin gene chr. 11 *Phenotype:* B+ = silent B-thal carrier mild, no symptoms B- = B-thal trait mild anemia, abnormal RBC indices