NPM1 and myelodysplastic syndrome: Non-isolated del(5q) MDS showed NPM1/5q 35.1 monoallelic loss in 42.5% of cases versus 2.3% in isolated MDS-del(5q); gross chromosome abnormalities and monosomies, as observed in high-risk MDS, were significantly related to NPM1 haploinsufficiency [24].