OBJECTIVETo analyze the clinical, laboratory characteristics and PIG-A gene mutations in patients of myelodysplastic syndromes (MDS) with PNH clones.

METHODS218 MDS patients diagnosed from August 2013 to August 2015 were analyzed. The PIG-A gene mutations were tested in 13 cases of MDS with PNH clones, 17 cases of AA-PNH and 14 cases of PNH selected contemporaneously by PCR and direct sequencing.

RESULTS13 (5.96%) MDS patients were detected with PNH clones (13/218 cases). 9 patients were treated with cyclosporin A (CsA). Patients showed hematological improvement (HI). There were significant differences between MDS-PNH and PNH patients in terms of granulocyte clone size, red cell clone size and LDH levels [19.2% (1.0%-97.7%) vs 60.2% (3.1%-98.0%), P=0.007; 4.3% (0-67.2%) vs 27.9% (2.5%-83.6%), P=0.026; 246 (89-2014) U/L vs 1137 (195-2239) U/L, P=0.049], while the differences were not statistically significant in patients between MDS-PNH and AA-PNH patients [19.2% (1.0%-97.7%) vs 23.2% (1.5%-96.0%), P=0.843; 4.3% (0-67.2%) vs 14.4% (1.1%-62.8%), P=0.079; 246 (89-2014) U/L vs 406 (192-1148) U/L, P=0.107]. PIG-A gene mutations were detected in 7 MDS-PNH patients, of them, six were missense mutations, one were frameshift mutation and four cases with the same mutation of c.356G>A (R119Q). The PIG-A gene mutations were also detected in 9/11 AA-PNH patients and 11/14 PNH patients, both of them had the mutation of c.356G>A (R119Q). The PIG-A gene mutations of MDS-PNH, AA-PNH, PNH patients were all small mutations, the majority of those (59%) were missense mutation and mainly located in exon 2.

CONCLUSIONMDS patients with PNH clones had better response to CsA, smaller PNH clone size. The PIG-A gene mutations of MDS-PNH patients mainly located in exon 2, which could be a mutational hotspot of these patients.