Bart's hydrops fetalis is lethal because:: (A) Hb Bart's cannot bind oxygen, (B) The excess a-globin form insoluble precipitates, (C) Hb Bart's cannot release oxygen to fetal tissues, (D) Microcytic red cells become trapped in the placental
Answer is C. c. Hb Bart's cannot release oxygen to fetal tissues(Ref: Nelson's 20/e p 2349-2352, Ghai 8/e p 341)As Hb Bart's consists of 4y chains, which have very high oxygen affinity, it cannot release oxygen to fetal tissues.