Ankyrin‐linked hereditary spherocytosis in an African–American kindred

Mutations of ankyrin‐1 are the most frequent cause of the inherited hemolytic anemia, hereditary spherocytosis (HS), in people of European ancestry. Ankyrin‐1, which provides the primary linkage between the erythrocyte membrane skeleton and the plasma membrane, has numerous isoforms generated by alternative splicing, alternate polyadenylation, use of tissue‐specific promoters, and alternate NH 2 or COOH‐termini. Mutation detection in erythrocyte membrane protein genes, including ankyrin, has been a challenge, primarily due to the large size of these genes, and the apparent frequent occurrence of HS‐associated null alleles. Using denaturing high‐performance liquid chromatography (DHPLC), we screened the ankyrin gene of the proband of a large, three generation African–American kindred with ankyrin‐deficient HS. DHPLC yielded an abnormal chromatogram for exon 1. Examination of the corresponding exon 1 sequence in genomic DNA from the proband revealed heterozygosity for a mutation of the initiator methionine (AT G to AT A Met 1 Ile). Coupled in vitro transcription/translation studies with rabbit reticulocyte lysates demonstrated that the wild‐type ankyrin erythroid cDNA initiates only from the known initiator methionine, indicating that the use of alternate initiator methionine is not a mechanism of isoform diversity in erythroid cells. The mutant ankyrin allele, unlike some initiator methionine mutations that utilize downstream codons for translation initiation, was associated with a null allele. This is the first report describing ankyrin‐linked HS in an African–American kindred. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.