A genomic deletion causes truncation of α-spectrin and ellipto-poikilocytosis.

We report on a truncated α-spectrin chain, spectrin(Exeter), associated with ellipto-poikilocytosis. Analysis of erythrocyte membranes of affected individuals revealed a truncated α-spectrin chain with normal amounts of spectrin dimer. In the proband and her father, one haploid set of α-spectrin cDNA lacked exons 11 and 12, leading to partial deletion of repeats α4 and α5 (83 amino acids) of the α-spectrin chain. In one allele of genomic DNA, a 3567bp deletion starting in intron 10 and ending in intron 12 of the SPTA1 gene was found. The common polymorphic SPTA1 α(LELY) allele was found in trans to the SPTA1αExeter allele in the proband. The proband had inherited the SPTA1Exeter allele from her father and the αLELY allele from her healthy, asymptomatic mother. This is the first report of an interstitial deletion in the SPTA1 gene associated with ellipto-poikilocytosis.