Also, atypical scenarios are reported raising additional challenges, for instance, individuals with MEN1 manifestations but negative genetic testing, non-functioning NETs (regarding the endocrine panel) that may be more difficult to be identified early unless the carrier status is already confirmed in one individual or a family, and a very aggressive neoplasia behavior with rapid multi-organ spreading [96,98,99]. The gene discussed is MEN1; the disease is neoplasm.