Clonal hematopoiesis as defined by polymorphic X-linked loci occurs infrequently in aplastic anemia.
We evaluated the methylation status of the X-linked gene phosphoglycerate kinase (PGK1) and the DXS 255 locus detected by probe M27 beta to study clonality in acquired aplastic anemia (AA). A total of 30 females were suitable for clonal analysis of peripheral blood polymorphonuclear cells (PMN) and mononuclear cells using a polymerase chain reaction-based procedure in 24 patients and Southern blotting in 9. Overall, 10 of 30 patients exhibited an imbalanced X-inactivation pattern. However, in 4 patients, analysis of constitutional DNA suggested a skewed methylation pattern and 2 further cases had to be excluded because of the lack of an appropriate control. A truly clonal pattern was thus established in 4 of 30 (13%) patients. In 7 patients who later developed clonal disorders of hematopoiesis, X-inactivation analysis did not predict this event in any case. In patients with a paroxysmal nocturnal hemoglobinuria phenotype, there was no correlation between the proportion of phosphatidylinositol glycan anchored protein (PIG-AP)-deficient blood cells and the corresponding X-inactivation pattern. X-inactivation analysis detected clonal hematopoiesis in only 3 of 10 patients with a deficiency in PIG-AP in the cell population under study, but sorting of nucleated cells on the basis of PIG-AP expression showed the clonal nature of PIG-AP-deficient cells. We conclude that the majority of patients with AA show polyclonal hematopoiesis using X-linked clonal analysis, but that minor clonal populations, such as PIG-AP-deficient cells, may not be detected unless sorted cell populations are separately analyzed.
Raghavachar
A
A
Department of Medicine III, University of Ulm, Germany.
Janssen
J W
JW
Schrezenmeier
H
H
Wagner
B
B
Bartram
C R
CR
Schulz
A S
AS
Hein
C
C
Cowling
G
G
Mubarik
A
A
Testa
N G
NG
Dexter
T M
TM
Hows
J M
JM
Marsh
J C
JC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000741:Anemia, Aplastic / Q000473:pathology*; D001483:Base Sequence; D002999:Clone Cells / Q000473:pathology*; D004303:Dosage Compensation, Genetic; D005260:Female; D005819:Genetic Markers; D006410:Hematopoiesis; D006801:Humans; D008745:Methylation; D008875:Middle Aged; D008969:Molecular Sequence Data; D010735:Phosphoglycerate Kinase / Q000235:genetics; D011110:Polymorphism, Genetic; D014960:X Chromosome
D005819:Genetic Markers; D010735:Phosphoglycerate Kinase