At 5 months of age, May–Grünwald–Giemsa (MGG) staining of kidney marrow and peripheral blood smears representing 9-11 individual fish per genotype (Fig. 6A-H) revealed an increase in the number of myelomonocytes (Fig. 6A-D, light-blue arrows) in the kidney marrow of a subset of animals with heterozygosity for asxl1 [asxl1+/−tet2+/+ (5 of 11); asxl1+/−tet2+/− (8 of 11) and asxl1+/−tet2−/− (3 of 10)], which is diagnostic of MPN. This evidence concerns the gene ASXL1 and myeloproliferative neoplasm.