There are >20 genes described to be mutated inNETs, with the most common being menin 1 (MEN1),death-domain-associated protein (DAXX) and ATRX chromatin remodeler(ATRX), which occur in 40–70% of sporadic G1–G3pancreatic NETs (PanNETs), and cyclin-dependent kinase inhibitor 1B(CDKN1B), which occurs in approximately 10% of sporadicG1–G3 small intestinal NETs (siNETs) (Jiaoet al. 2011, Francis et al. 2013, Di Domenico et al. 2017, Scarpa et al. 2017, van Riet et al. 2021). The gene discussed is ATRX; the disease is small intestine neuroendocrine neoplasm.