The Somatic Mutation of PIG-A Gene and the Expressions of EGR-1 and WT1 Genes in Bone Marrow Cells of the Patients with Paroxysmal Nocturnal Hemoglobinuria

To investigate the somatic mutations of PIG-A gene and the expressions of EGR-1 and WT1 genes in the bone marrow cells of the patients with Paroxysmal nocturnal hemoglobinuria, then explore the characteristics of PIG-A gene mutation in Chinese patients with PNH and the possible mechanism of PNH clonal expansion related to EGR-1 and WT1 genes.

The quantities of CD55⁻ cells and CD59⁻ cells in both peripheral blood and bone marrow were examined with flow cytometric assay(FCM), and then sorting CD59⁻ cells from bone marrow mononuclears (BMMNCs). The mutant segments of PIG-A gene were identified by DNA sequencing; The expressions of EGR-1 and WT1 mRNA in CD59⁻ and CD59⁺ BMMNC were measured with semiquantitive RT-PCR.

Nine in sixteen patients with PNH and one in four patients with AA-PNH were measured for their PIG-A gene mutation. Five single base substitution were found, including A→G, G→T, A→T, T→G and G→C, resulting in one consense and seven missense mutations. Each of 3 PNH patients had more than two point mutations of PIG-A gene. Insert or deletion mutation of PIG-A gene were not found. The relative mRNA expressions of EGR-1and WT1 genes in CD59⁻ BMMNC, CD59⁺ BMMNC of PNH or AA-PNH patient and BMMNC of normal controls were (1.00±0.11), (0.86±0.14), (0.85±0.06) and (1.06±0.16), (0.90±0.14), (0.88±0.06), the expression in CD59⁻ BMMNC was significantly higher than that in CD59⁺ BMMNC or normal controls (p<0.05). There was no significant difference between the expression in CD59⁺ BMMNC and normal controls(p>0.05). The relative mRNA expressions of EGR-1 and WT1 in BMMNC of PNH and AA-PNH cases were positively correlated with the proportion of CD59⁻ cells(coefficient correlation was 0.509 and 0.481 respectively, p<0.05), but not related to the proportion of CD59⁺ cells.

The PIG-A gene mutation in some Chinese patients mainly manifested as single base substitution, occurred at random sites and without hot spot, the overexpression of EGR-1 and WT1 genes in PNH clone could promote the abnormal clone expansion.

No relevant conflicts of interest to declare.