Frameshifting point mutation in MYB gene in granulocytic DNA from a patient with myelofibrosis with myeloid metaplasia. Insertion of a cytosine base (arrow; c.1992insC and p.S599EfsX605; GenBank reference sequences NM_005375 and NP_005366, respectively) leads to a frameshift with premature stop codon generation. This was the only nonsynonymous point mutation detected in analysis of MYB gene (25 patients) and EP300 KIX domain. Bottom: wild-type; middle: patient sense sequence; top: patient antisense sequence. Patient sequences demonstrate confused sequence expected for mixed clonality insertional mutation.