Amino-acid substitution in alpha-spectrin commonly coinherited with nondominant hereditary spherocytosis

作者：Tse WT; Gallagher PG; Jenkins PB; Wang YP; Benoit L; Speicher D; Winkelmann JC; Agre P; Forget BG; Marchesi SL

来源：American Journal of Hematology, 1997, 54(3): 233-241.

DOI：10.1002/(SICI)1096-8652(199703)54:3<233::AID-AJH10>3.0.CO;2-E

• hereditary spherocytosis
• alpha-spectrin gene
• polymorphism, mutation
• recessive disorder

Nondominant hereditary spherocytosis (ndHS) is a disorder characterized in some patients by severe hemolytic anemia and marked deficiency of erythrocyte spectrin. This report describes the identification of a variant spectrin chain, alpha-spectrin Bughill or alpha(BH), that is associated with this disorder in a number of patients. Tryptic maps of spectrin from affected individuals revealed an acidic shift in isoelectric point of the all domain peptides at 46 kD and 35 kD. A point mutation at codon 970 of the alpha-spectrin gene (GCT-->GAT), that changes the encoded amino acid from an alanine to an aspartic acid, was identified in genomic DNA of affected patients. The alpha(BH) variant was present in 8 patients with ndHS from five different kindreds but was absent in 4 patients from two other kindreds. The 8 ndHS patients with the alpha(BH) variant appeared to be homozygous for the alpha(BH) variant by analysis of peptide maps of limited tryptic digests of erythrocyte spectrin. However, following genomic DNA analysis, only 2 of these patients were true homozygotes, whereas 6 were found to be doubly heterozygous for the alpha(BH) allele and a second, presumably abnormal, alpha-spectrin gene. These results suggest that, in these 6 patients, the second alpha-spectrin allele is in fact associated with one or more genetic defect(s), causing decreased accumulation of alpha-spectrin. The pattern of transmission of the alpha(BH) allele in certain families suggests that the alpha(BH) amino-acid substitution is not itself responsible for ndHS but is more likely a polymorphic variant that, in some but not all cases, is in linkage disequilibrium with another uncharacterized alpha-spectrin gene defect that itself is a cause of ndHS.

• 出版日期1997-3