Fig. 1

a Computed tomography (CT) demonstrating a right adrenal mass measuring 3.7 × 3.6 cm located between the liver and the upper pole of the right kidney. The left side shows a normal Y-shaped adrenal gland. b Marked in red is the upper reference limit for hematocrit levels. Patient had elevated hematocrit levels prior to the surgery and the hematocrit remained within the normal reference range for over a year after the surgery. c Genetic testing of the genomic DNA revealed a heterozygous mutation (c.267-1_267delGGinsTA; arrows) of the IRP1 gene in tumor, but not in blood. The JAK2 mutation was not detected in the patient’s tumor. d Alignment of base pair sequences of IRP1 in human, chimp, gorilla, rhesus, baboon, mouse, rabbit, and zebrafish, indicating its vital role in gene splicing. e. FISH analysis showed IRP1 deletion during metaphase in the tumor cells. Centromeric marker (green) and probe (red) are specific markers for chromosome 9 and IRP1. f Effects of mutations around splicing sites were predicted by Human Splicing Finder (HSF)