Nachtigall LB, Guarda FJ, Lines KE, et al. - In this retrospective record review and genetic analysis, researchers determined the prevalence of clinical Multiple Endocrine Neoplasia type 1 (MEN-1) with primary hyperparathyroidism (PHP) in patients with acromegaly and describe their clinical characteristics, as well as assessed the genetic basis for the coexistence of acromegaly and PHP. Four hundred fourteen patients with acromegaly were included in this analysis. Clinical MEN-1, defined by the presence of at least one other MEN-1-associated tumor, was present in 6.6% of patients with acromegaly. In patients with coexisting PHP, acromegaly was diagnosed at an older age with a higher prevalence of malignancies (specifically breast and thyroid) than those with isolated acromegaly. in patients with clinical MEN-1 and negative genetic testing, a distinct phenotype for mutations previously associated with this syndrome is identified.