Hippo kinase STK4 is located in the 20q CDR and downregulated in MDS and MPN patients with del(20q). (A) Row-normalized heatmap of gene expression in CD34⁺ bone marrow cells from 6 del(20q) MDS patients (left) compared with CD34⁺ bone marrow cells from 10 healthy controls (right). The top 25 significantly downregulated genes in del(20q) patients, along with their chromosomal position in the genome are depicted. Data are from GEO accession number GSE58831. (B) STK4 gene expression measured by microarray in total peripheral blood from healthy controls (blue) and MPN patients with polycythemia vera (PV, pink) or primary MF (red). Data are from GEO accession number GSE26049. (C) STK4 gene expression measured by microarray in peripheral blood granulocytes from healthy controls (blue) and MPN patients with polycythemia vera (PV, pink) or MF (red). Samples identified as del(20q) are indicated. Data are from GEO accession number GSE54646. (D) An NCBI chromosome ideogram showing the q arm of chromosome 20. Minimal CDR measured by array comparative genomic hybridization in a cohort of 30 MDS patients¹⁶  is indicated in red. Positions of genes previously implicated in the pathogenesis of myeloid malignancies are indicated in gray. The position of STK4 is indicated in black. Statistical significance was determined by a 2-tailed Student t test. *P < .05, ***P < .001. n.s., not significant. Data in panel A are from Gerstung et al,³⁷  data in panel B are from Skov et al³⁸  and data in panel C are from Rampal et al.³⁹