Detection of somatic mutations of the PIG-A gene in Brazilian patients with paroxysmal nocturnal hemoglobinuria

Abstract

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal syndrome characterized by intravascular hemolysis mediated by complement, thrombotic events and alterations in hematopoiesis. Basically, the molecular events which underlie the complexity of the syndrome consist of the absence of the glycosylphosphatidylinositol (GPI) anchor as a consequence of somatic mutations in the PIG-A gene, located on the X chromosome. The GPI group is responsible for the attachment of many proteins to the cytoplasmic membrane. Two of them, CD55 and CD59, have a major role in the inhibition of the action of complement on the cellular membrane of blood cells. The absence of GPI biosynthesis can lead to PNH. Since mutations in the PIG-A gene are always present in patients with PNH, the aim of this study was to characterize the mutations in the PIG-A gene in Brazilian patients. The analysis of the PIG-A gene was performed using DNA samples derived from bone marrow and peripheral blood. Conformationsensitive gel electrophoresis was used for screening the mutation and sequencing methods were used to identify the mutations. Molecular analysis permitted the identification of three point mutations in three patients: one G®A transition in the 5 portion of the second intron, one T®A substitution in the second base of codon 430 (Leu430®stop), and one deletion DA in the third base of codon 63. This study represents the first description of mutations in the PIG-A gene in a Brazilian population.

Hemoglobinúria paroxística noturna: da fisiopatologia ao tratamento

“…Os trabalhos publicados estudando pacientes brasileiros analisaram as mutações do gene PIG-A, buscando identificar o perfil de mutação no Brasil. O perfil encontrado foi semelhante nos dois trabalhos: predomínio de mutações de ponto com presença de mutações novas, não anteriormente relatadas 38,39 . Estes dados confirmaram estudos prévios em relação à grande variabilidade das mutações de PIG-A encontradas em HPN nas diferentes populações e também o fato de que elas não apresentam correlação com o curso clínico da doença [40][41][42] .…”

Frequency of paroxysmal nocturnal hemoglobinuria in patients attended in Belém, Pará, Brazil

“…This makes these cells vulnerable to lysis mediated by complement which results in hemolytic anemia, a certain degree of bone marrow insufficiency and the release of large amounts of free hemoglobin into the plasma, which can lead to an increase in the consumption of nitric oxide and clinical manifestations that include fatigue, abdominal pain, esophageal spasms, erectile dysfunction and various degrees of thrombosis (classic or subclinical PNH). (1,7,8) …”

Frequency of paroxysmal nocturnal hemoglobinuria in patients attended in Belém, Pará, Brazil

“…This makes these cells vulnerable to lysis mediated by complement which results in hemolytic anemia, a certain degree of bone marrow insufficiency and the release of large amounts of free hemoglobin into the plasma, which can lead to an increase in the consumption of nitric oxide and clinical manifestations that include fatigue, abdominal pain, esophageal spasms, erectile dysfunction and various degrees of thrombosis (classic or subclinical PNH). (1,7,8) In some special situations, PNH can be associated with other specific disorders of the bone marrow such as aplastic anemia, myelodysplastic syndrome or other myelopathies including myelofibrosis. (9)(10)(11)(12) Estimated survival for untreated patients with classic or subclinical PNH is approximately 8 years with the main causes of death being thrombotic complications and progressive pancytopenia.…”