Molecular Defect of Spectrin in the Family of a Child with Congenital Hemolytic Poikilocytic Anemia

Abstract

We present the study of a black family in which the proband suffered from a severe neonatal hemolytic anemia with poikilocytosis. Both the parents, sister's, and brother's proband were clinically normal. The presence of poikilocytes in proband led to a search for a red cell membrane skeleton defect. Owing to recent improvements in the erythrocyte membrane knowledge, it is now possible to approach the diagnosis by means of biochemical evaluation of both parents, even if they are asymptomatic. So, the first time discovery of a spectrin self-association defect in both parents allowed us to suspect double inheritance of this abnormality in the proband. A complete morphological and biochemical evaluation of the family allowed us to propound the diagnosis of heterozygous type I hereditary elliptocytosis (HE) for both parents and the sister and the diagnosis of homozygous type I HE for the proband owing to the following reasons: slight ovalocytosis was present in both parents and the sister; cell deformability ektacytometric studies gave the same profiles of curve as those observed in patients with HE. Defective spectrin dimer self-association found in both parents was also observed in the sister and proband, associated with the same abnormal spectrin digest pattern, namely a decrease in the amount of a 80,000-dalton peptide and a corresponding increase in a 74,000-dalton peptide. However, clinical presentation of the proband was consistent either with hereditary pyropoikilocytosis or homozygous hereditary elliptocytosis; erythrocyte thermal sensitivity studies in the proband could not be conclusive because of the presence of transfused cells. Both these diagnoses are discussed in detail.(ABSTRACT TRUNCATED AT 250 WORDS)