A patient with paroxysmal nocturnal hemoglobinuria bearing four independent PIG-A mutant clones.
Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by clonal blood cells that are deficient in the surface expression of glycosylphosphatidylinositol-anchored proteins due to somatic mutation in the X-linked gene PIG-A. In some patients, more than one abnormal clone may be present. Analysis of bulk DNA/RNA from granulocytes has been useful in identifying the predominant PIG-A mutation in each patient. However, it is often not useful in determining the presence of minor clones. Many patients have cells with partial deficiency. Here, we analyzed the PIG-A gene in two B-cell lines bearing complete or partial deficiencies, cells of hematopoietic progenitor colonies and peripheral blood granulocytes from the same patient. We found that two B-cell lines had different mutations, the granulocytes contained at least two mutants, and the hematopoietic progenitors contained four mutants. Three of the four were shared by B cells and/or granulocytes whereas the other one was found only in the hematopoietic progenitors. The partial deficiency was caused by a point mutation near an alternative splice site within exon 2 that resulted in partial decreases of activity and quantity of the full-length transcript. These results further show the oligoclonal nature of PNH and differences in extent of expansion among mutant clones.
Nishimura
J
J
Department of Hematology and Oncology, Osaka University Medical School, Suita, Japan.
Inoue
N
N
Wada
H
H
Ueda
E
E
Pramoonjago
P
P
Hirota
T
T
Machii
T
T
Kageyama
T
T
Kanamaru
A
A
Takeda
J
J
Kinoshita
T
T
Kitani
T
T
D017398:Alternative Splicing; D001402:B-Lymphocytes; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017931:DNA Primers; D016368:Frameshift Mutation; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006098:Granulocytes / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D006457:Hemoglobinuria, Paroxysmal / Q000097:blood / Q000235:genetics*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis; D017384:Sequence Deletion; D014960:X Chromosome
D017931:DNA Primers; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D011994:Recombinant Proteins; C080086:phosphatidylinositol glycan-class A protein