Red blood cell and DNA investigations. (A) Family pedigrees showing mutation segregation. (B) Blood film smears (MGG) for proband 1 and his mother. (C) Multiple interspecies protein sequence alignment of KCNN4 in the region of residue 352. (D) KCNN4 transcript sequencing: (upper) WT sequence and (lower) transcript with mutation c.1055G>A (p.Arg352His). (E) Red cell osmotic fragility test using osmotic gradient ranging from 0.1% to 1% of NaCl solution. (Left) At T0 and at T24-hour incubation at 37°C for a control and individuals III-3 and IV-3 from family 1. (Right) After T24-hour incubation at 4°C or 37°C for a control and individual III-2 from family 1.