Hereditary nonspherocytic hemolytic anemia caused by red cell glucose-6-phosphate isomerase (GPI) deficiency in two Portuguese patients: Clinical features and molecular study

Abstract

Glucose-6-phosphate isomerase (GPI) deficiency cause hereditary nonspherocytic hemolytic anemia (HNSHA) of variable severity in individuals homozygous or compound heterozygous for mutations in GPI gene. This work presents clinical features and genotypic results of two patients of Portuguese origin with GPI deficiency. The patients suffer from a mild hemolytic anemia (Hb levels ranging from 10 to 12.7g/mL) associated with macrocytosis, reticulocytosis, hyperbilirubinemia, hyperferritinemia and slight splenomegaly. Genomic DNA sequencing revealed in one patient homozygosity for a new missense mutation in exon 3, c.260G>C (p.Gly87Ala), and in the second patient compound heterozygosity for the same missense mutation (p.Gly87Ala), along with a frameshift mutation resulting from a single nucleotide deletion in exon 14, c.1238delA (p.Gln413Arg fs*24). Mutation p.Gln413Arg fs*24 is the first frameshift null mutation to be described in GPI deficiency. Molecular modeling suggests that the structural change induced by the p.Gly87Ala pathogenic variant has direct impact in the structural arrangement of the region close to the active site of the enzyme.

Clinical and Molecular Spectrum of Glucose-6-Phosphate Isomerase Deficiency. Report of 12 New Cases

“…The present cohort of GPI deficient patients represents the largest series so far described in a single study, collecting retrospective information and follow-up data over a median period of 18 years. All the cases were never reported before, consistently increasing the number of GPI patients reported in literature (Kugler and Lakomek, 2000; Clarke et al, 2003; Repiso et al, 2006; Warang et al, 2012; Adama van Scheltema et al, 2015; Zhu et al, 2015; Manco et al, 2016; Jamwal et al, 2017; Zaidi et al, 2017; Burger et al, 2018; Kedar et al, 2018; Mojzikova et al, 2018).…”

“…The gene locus encoding GPI is located on chromosome 19q13.1 and contains 18 exons (Walker et al, 1995). So far, about 60 cases of GPI deficiency have been described, and more than 40 mutations have been reported at the nucleotide level (Kugler and Lakomek, 2000; Clarke et al, 2003; Repiso et al, 2006; Zhu et al, 2015; Manco et al, 2016; Jamwal et al, 2017; Zaidi et al, 2017; Kedar et al, 2018; Mojzikova et al, 2018). Missense mutations are the most common, but non-sense and splicing mutations have also been observed.…”

Oxidation Resistance 1 Modulates Glycolytic Pathways in the Cerebellum via an Interaction with Glucose-6-Phosphate Isomerase

“…In addition, the molecular detail of enzymatic dysfunction can be confounded by the presence of compound heterozygous GPI mutations, where an unknown complement of mutant catalytic dimers or heterodimers will form in vivo [ 30 , 33 , 34 , 60 , 62 , 63 , 65 – 67 , 70 ]. A previous study examined mutants in the context of the GPI three-dimensional data and classified them in distinct classes: those that alter GPI structure and those that disrupt either its oligomerization or active site [ 51 ]; thus it was hypothesised that mutations influencing protein folding would affect both the enzymatic and neurotrophic activities of GPI leading to haemolytic and neurological symptoms in patients, while mutations affecting the active site would disrupt the enzymatic activity alone [ 30 , 51 , 70 , 86 ]. Here, we demonstrated that there were limited effects on binding affinity between Oxr1 and the selected pathogenic Gpi1 mutations, although the shortest Oxr1-C isoform interacted with greater affinity to the L339P mutant, a substitution that causes anaemia with neuromuscular involvement when combined with a second H20P mutant GPI allele [ 30 ].…”

“…Clinically, GPI mutations significantly reduce the catalytic activity of the protein; these measurements are made typically from patients’ erythrocytes, although much of the molecular data linking phenotype and genotype are based-around the physiochemical properties of the GPI protein, such as in vitro thermostability or electrophoretic mobility [30–32, 34, 59–65, 67, 69, 72, 83–85]. In addition, the molecular detail of enzymatic dysfunction can be confounded by the presence of compound heterozygous GPI mutations, where an unknown complement of mutant catalytic dimers or heterodimers will form in vivo [30, 33, 34, 60, 62, 63, 65–67, 70]. A previous study examined mutants in the context of the GPI three-dimensional data and classified them in distinct classes: those that alter GPI structure and those that disrupt either its oligomerization or active site [51]; thus it was hypothesised that mutations influencing protein folding would affect both the enzymatic and neurotrophic activities of GPI leading to haemolytic and neurological symptoms in patients, while mutations affecting the active site would disrupt the enzymatic activity alone [30, 51, 70, 86].…”

A Case Report of Congenital Non-spherocytic Hemolytic Anemia in a Patient from India

“…Patients with CNSHA tend to have a normal hemoglobin structure and stability. Different enzymes deficiencies have been reported such as pyruvate kinase deficiency, hexokinase deficiency [ 2 ], pyrimidine 5’nucleotidase deficiency [ 3 ] and homozygous glucose phosphate isomerase (GPI) deficiency [ 4 ] causing a decrease in adenosine triphosphate (ATP) levels which eventually leads to RBC death and hemolysis [ 5 - 6 ]. Warang et al used a molecular modeling to show that mutations of L487F can cause a loss of the ability of GPI to dimerize, causing the RBCs to have lower thermostability and significant changes in metabolisms leading to hemolysis [ 7 ].…”