In Reply.—Dr Smith, Drs Grover and Wethers, Dr Detter and colleagues, and Dr Rao have correctly emphasized that citrate agar electrophoresis at an acid pH will not differentiate homozygous sickle cell anemia from sickle cell variants associated with thalassemia syndromes and HPFH. It will facilitate the detection of small amounts of Hb A and clearly separate Hb F from Hb S.1 On that point I stand corrected.
As stated in the editorial (Journal 1979;133:1235-1236) and as presented in the article by Rubin and Rowley (Journal 1979;133:1248-1250), additional laboratory studies on the newborn and on family members are absolutely mandatory before a definitive diagnosis of homozygous sickle cell anemia can be made. My concerns are with the responsibilities of the state screening programs. What will the pediatrician do with information provided by repeated testing that confirms the original result of "consistent with sickle cell anemia"? This is the problem.