Simultaneous (AC)_n microsatellite polymorphism analysis and single‐stranded conformation polymorphism screening is an efficient strategy for detecting ankyrin‐1 mutations in dominant hereditary spherocytosis

Abstract

Summary. Nonsense/stop mutations in the ankyrin-1 gene (ANK1) are a major cause of dominant HS (dHS) (frequency of 23% in German dHS patients). To date, no common mutation has been found and therefore a simple mutation screening is not feasible. The reduced expression of one cDNA allele in the (AC) n microsatellite polymorphism of the ankyrin-1 gene, as seen in about 20% of Czech patients with dHS, may identify candidates with a possible frameshift/ nonsense mutation. In order to verify the efficiency of this screening we screened the ankyrin-1 gene of 22 Czech dHS patients for both the reduced cDNA allele expression in the frequent (AC) n and the common exonic 26/39 polymorphisms, as well as for polymerase chain reaction (PCR) single-stranded conformation polymorphisms in any one of the 42 exons of ANK1. Anomalous PCR products were sequenced. We found seven new ANK1 frameshift/nonsense mutations in nine patients with, but in none of six patients without, a reduced cDNA allele expression (efficiency of 78%). We conclude that screening of dHS patients for such a reduced allele expression in common ANK1 polymorphisms is an efficient procedure for the identification of candidates for frameshift/nonsense mutations in the ankyrin-1 gene.

Mutational characteristics of ANK1 and SPTB genes in hereditary spherocytosis

“…After a literature search related to HS, 50 cases including 31 ANK1 and 19 SPTB mutations were identified. These reports provided laboratory and clinical data, such as Hb level, splenectomy, and aplastic crisis which allowed calculation of the difference of Hb level according to mutated genes or the frequencies of splenectomy and aplastic crisis according to located domain of mutation in each gene.…”

A novel ENU-generated truncation mutation lacking the spectrin-binding and C-terminal regulatory domains of Ank1 models severe hemolytic hereditary spherocytosis

“…In many cases, the human mutant ANK1 alleles are hypomorphic—but this is often adequately (or fully) compensated by expression from the WT ANK1 allele [5,33]. Ankyrin-1 haploinsufficiency results in reduced expression or stability of other membrane structural components, including band 3 and the spectrins [2,33]. Although some cases of recessive inheritance have been reported, de novo or dominantly inherited Ank1 HS are much more common.…”

Ankyrin‐linked hereditary spherocytosis in an African–American kindred

“…Biochemical studies typically only reveal ankyrin deficiency and do not provide clues to where causative mutations are located. Finally, decreased ankyrin mRNA has been observed in up to 30% of HSassociated ankyrin gene mutations, making cDNA-based mutation detection strategies problematic [33].…”