Guanine nucleotide binding protein (G protein), beta polypeptide 1(GNB1) encodes a beta subunit of heterotrimeric G-proteins. Recurrent missense mutations at the Lys57 codon of GNB1 (eg, p.K57E, p.K57N, p.K57T) in the WD40 repeat motif have been reported in less than 5 % of myelodysplasia/secondary acute myeloid leukemia and de novo AML. The lysine at codon 57 of GNB1 has been reported to interact with the G-protein subunit alpha(GNAS), which itself has also been shown to be recurrently mutated in myelodysplasia. According to some studies, Lys57Ala mutations lead to altered downstream signaling in some G-protein coupled receptor signaling pathways. Overall, these findings suggests that mutations at Lys57 of GNB1 are pathogenic. In addition, frameshift mutation at codon 53 of GNB1 has also been described in myelodysplasia.