Band 4.2 Shiga: 317 CGC → TGC in compound heterozygotes with 142 GCT → ACT results in band 4.2 deficiency and microspherocytosis

Abstract

A novel compound heterozygous mutation of 317 CGC-->TGC with 142 GCT-->ACT in human red cell band 4.2 deficiency is described. A proband and his son suffered from compensated haemolysis with nearly complete deficiency of red cell band 4.2. Their red cell morphology exhibited microspherocytosis resembling classic hereditary spherocytosis (HS). Sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed band 4.2 to be nearly missing (< 1% of normal controls) with the presence of 74 kD and 72 kD isoforms in trace amounts. Other family members (daughters older and younger than the son) exhibited nearly normal amounts of 72kD as a wild form of band 4.2 on SDS-PAGE with the presence of the 74kD isoform in a trace amount. The proband and his son demonstrated two compound heterozygous mutations in trans: i.e. nucleotide (nt) 949 CGC-->TGC (codon 317 Arg-->Cys) in exon 7 and nt 424 GCT--ACT (codon 142 Ala-->Thr) in exon 3 of the band 4.2 gene. The two daughters demonstrated only the mutation of nt 949 CGC-->TGC in exon 7 in heterozygous states, but no 142 mutation. Therefore the proband and his son were compound heterozygotes of these two mutations in trans. It is interesting to note that the 74 kD isoform of band 4.2 protein existed in a trace amount in the two daughters in spite of the absence of the 142 Ala-->Thr mutation. In addition, even in the presence of the 142 mutation in one allele in the proband and his son, their red cell morphology demonstrated classic HS with microspherocytosis, although a homozygous state of the 142 mutation known as the Nippon type of band 4.2 deficiency exhibits ovalostomatocytosis.

Electron microscopic evidence of impaired intramembrane particles and instability of the cytoskeletal network in band 4.2 deficiency in human red cells

“…Among them, we recently identified three probands with different kinds of mutations of the band 4.2 gene [Inoue et al, 1994;Kanzaki et al, 1995a,b], with no abnormalities on the band 3 gene. They are band 4.2 Komatsu, which is a homozygote of nt 523 GAT + TAT: codon 175 Asp + Tyr in exon 4 [Kanzaki et al, 1995b], band 4.2 Nippon as a homozygote of nt 424 GCT -+ ACT: codon 142 Ala -+ Thr in exon 3 [Bouhassira et al, 1992;Inoue et al, 1994;Yawata, 1994a1, and band 4.2 Shiga as a compound heterozygote of two mutations, i.e., nt 949 CGC GCT -+ ACT (codon 142 Ala --f Thr) in exon 3 [Kanzaki et al, 1995al. Band 4.2 protein was totally absent in band 4.2 Komatsu, but was present in a trace amount in the other two band 4.2 deficiencies.…”

Investigating the key membrane protein changes during in vitro erythropoiesis of protein 4.2 (-) cells (mutations Chartres 1 and 2)

“…[14][15][16] To date, nine mutations in EPB42 have been associated with hereditary spherocytosis, 6,[17][18][19][20][21][22] some of these mutations influence protein 4.2 stability and band 3-ankyrin-1 binding. 8,23 Protein 4.2 deficiency in humans causes a severe reduction in the marker of self, 24 CD47 (by approximately 80%), 6,25,26 suggesting an association between protein 4.2 and CD47.…”

Protein-4.2 association with band 3 (AE1, SLCA4) in Xenopus oocytes: effects of three natural protein-4.2 mutations associated with hemolytic anemia

“…Five lead to the premature termination of translation. 17,[21][22][23][24] Other protein-4.2 variants result from missense mutations that yield amino acid substitutions: protein 4.2 Nippon (GCTϾACT; A142T 25 ; occurs sporadically in the Japanese population and has been encountered once in whites), 26 protein 4.2 Tozeur (CGAϾCAA; R310Q), 27 protein 4.2 Shiga (CGCϾTGC; R317C), 28 and protein 4.2 Komatsu (GATϾTAT; D175Y). 29 Although there is a strict correlation between the occurrence of HS and the presence of these mutations (in homozygous or compound heterozygous states), the fact that these mutations are the direct cause of the absence of protein 4.2 has not been formally established.…”