Mutation analysis of the PIG-A gene in Korean patients with paroxysmal nocturnal haemoglobinuria

Abstract

Aim: Paroxysmal nocturnal haemoglobinuria (PNH) is caused by deficient biosynthesis of the glycosylphosphatidylinositol (GPI) anchor in haemopoietic stem cells. Mutation of the phosphatidylinositol glycan class A (PIG-A) gene, an X linked gene that participates in the first step of GPI anchor biosynthesis, is responsible for PNH. The characteristics of somatic mutation of the PIG-A gene in Korean patients with PNH were studied. Methods: Twenty four patients with PNH were selected. Ham tests and sucrose haemolysis tests were carried out on all patients. The expression of CD59 in erythrocytes and granulocytes was investigated in 14 and five patients, respectively, to confirm the diagnosis. Dideoxy fingerprinting (ddF) was used to screen mutations, and direct sequencing of DNA was performed to characterise the mutations. Results: Gene mutation was detected in 12 of the 24 patients. The other 12 patients were negative in ddF screening. Ten new mutations and two known mutations were detected. The mutations consisted of five deletions, six substitutions, and one insertion. These mutations resulted in six premature terminations, three abnormal splicings, one missense mutation in exon 2, and two nonsense mutations. Two patients with venous thrombosis showed mutations in exon 3 only. Substitution mutations were seen in six patients and frameshift mutations in the other six. Conclusions: There were 10 new mutations among the 12 mutations in the Korean patients with PNH and the characteristics of the mutations varied, with no significant hot spots in sites or types. P aroxysmal nocturnal haemoglobinuria (PNH) is a clonal stem cell disorder. The pathogenic mechanism of PNH is a deficiency of glycosylphosphatidylinositol (GPI) anchored proteins, which results in an abnormal sensitivity of red cells to complement.

Detailed immunophenotypic characterization of different major and minor subsets of peripheral blood cells in patients with paroxysmal nocturnal hemoglobinuria

“…Such phenotypic defect is due to a somatic mutation in the phosphatidylinositolglycan complementation Class A (PIG‐A) gene, located in human chromosome X at Xp22.1, which encodes for an enzyme required for the synthesis of GPI 2‐4 . Until now, a relatively high number of mutations have been reported in the PIG‐A gene, most corresponding to single‐point mutations, including substitution of one base and insertion and deletion of nucleotides leading to either the formation of a terminal codon close to the mutated sequence or an altered mRNA splicing; in contrast, mutations derived from insertion or deletion of relatively long sequences of nucleotides are rarely observed 3,5‐8 …”

Clonal Cell Proliferation in Paroxysmal Nocturnal Hemoglobinuria: Evaluation of PIGA Mutations and T-cell Receptor Clonality

“…The consensus is that a PIGA mutation per se is not sufficient to induce clonal expansion; additional clonal selection by extrinsic factors and intrinsic clonal evolution is required [8]. More than 20 genes localized on various autosomes are known to mediate GPI biosynthesis and attachment to proteins, and mutation in those genes also triggers PNH development [23242526].…”

COVID-19: ABC System and LBP-like Function of ORF7a Activate Monocytes to Induce Diabetes

“…Glycos_transf_1 domain protein transfer UDP, ADP, GDP or CMP linked sugars to various substrates, including glycogen, fructose 6-phosphate, and lipopolysaccharide. Glycos_transf_1 can take part in various biosynthetic processes, including exopolysaccharide biosynthesis and lipopolysaccharide core biosynthesis 117 . PglL_A domain (Interpro entry: IPR031726) is a protein glycosylation ligase domain.…”