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Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal blood disorder characterized by hemolysis and a high risk of thrombosis, that is due to a deficiency in several cell surface proteins that prevent complement activation. Its origin has been traced to a somatic mutation in the PIG-A gene within hematopoietic stem cells (HSC). However, to date the question of how this mutant clone expands in size to contribute significantly to hematopoiesis remains under debate. One hypothesis posits the existence of a selective advantage of PIG-A mutated cells due to an immune mediated attack on normal HSC, but the evidence supporting this hypothesis is inconclusive. An alternative (and simpler) explanation attributes clonal expansion to neutral drift, in which case selection neither favours nor inhibits expansion of PIG-A mutated HSC. Here we examine the implications of the neutral drift model by numerically evolving a Markov chain for the probabilities of all possible outcomes, and investigated the possible occurrence and evolution, within this framework, of multiple independently arising clones within the HSC pool. Predictions of the model agree well with the known incidence of the disease and average age at diagnosis. Notwithstanding the slight difference in clonal expansion rates between our results and those reported in the literature, our model results lead to a relative stability of clone size when averaging multiple cases, in accord with what has been observed in human trials. The probability of a patient harbouring a second clone in the HSC pool was found to be extremely low ([Formula: see text]). Thus our results suggest that in clinical cases of PNH where two independent clones of mutant cells are observed, only one of those is likely to have originated in the HSC pool.
This article was published in the following journal.
Name: PLoS computational biology
In the original publication of this article, Tables 2, 3 and 4 were published incorrectly. The corrected tables 2, 3 and 4 are given in the following pages.
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease characterized by intravascular hemolysis, thrombophilia, and marrow failure. Its phenotype is due to absent or reduced expressio...
Thrombosis is the prognostic factor with the greatest effect on survival in patients with paroxysmal nocturnal hemoglobinuria (PNH), who lack dozens of membrane surface proteins. We recently described...
This meta-analysis aimed to evaluate the risk of clonal evolution of granulocyte colony-stimulating factor (G-CSF) in acquired aplastic anemia (AA), and whether the use of G-CSF increases the occurren...
This study is a collection of data to evaluate safety and characterize progression of Paroxysmal Nocturnal Hemoglobinuria (PNH).
The purpose of this study is to assess the pharmacokinetics (PK), pharmacodynamics (PD), safety, and efficacy of ALXN1210 in pediatric patients with paroxysmal nocturnal hemoglobinuria (PN...
This study is designed to better understand the molecular biology of paroxysmal nocturnal hemoglobinuria (PNH) and to determine if prion protein (PrP) functions in long term hematopoietic ...
rVA576 for patients with Paroxysmal Nocturnal Hemoglobinuria (PNH).
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematological disorder, which can cause arterial or venous thrombosis. The frequency of PNH in young patients (< 50 year...
A condition characterized by the recurrence of HEMOGLOBINURIA caused by intravascular HEMOLYSIS. In cases occurring upon cold exposure (paroxysmal cold hemoglobinuria), usually after infections, there is a circulating antibody which is also a cold hemolysin. In cases occurring during or after sleep (paroxysmal nocturnal hemoglobinuria), the clonal hematopoietic stem cells exhibit a global deficiency of cell membrane proteins.
A parasomnia characterized by paroxysmal episodes of choreoathetotic, ballistic, dystonic movements, and semipurposeful activity. The episodes occur during non-rapid eye movement sleep and typically recur several times per night. (Neurology 1992 Jul;42(7 Suppl 6):61-67; Adams et al., Principles of Neurology, 6th ed, p391)
A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313)
Involuntary shock-like contractions, irregular in rhythm and amplitude, followed by relaxation, of a muscle or a group of muscles. This condition may be a feature of some CENTRAL NERVOUS SYSTEM DISEASES; (e.g., EPILEPSY, MYOCLONIC). Nocturnal myoclonus is the principal feature of the NOCTURNAL MYOCLONUS SYNDROME. (From Adams et al., Principles of Neurology, 6th ed, pp102-3).
The presence of free HEMOGLOBIN in the URINE, indicating hemolysis of ERYTHROCYTES within the vascular system. After saturating the hemoglobin-binding proteins (HAPTOGLOBINS), free hemoglobin begins to appear in the urine.