MEN1 and acromegaly: Conversely, MEN1 mutations have been described in 1.2% of sporadic acromegaly patients younger than 30 years [80] The prevalence of patients with acromegaly and MEN1 phenotype (defined as occurrence of at least one other MEN1-associated tumour) has been noted in 6.6% of 414 patients with acromegaly, but the prevalence of MEN1 mutations in this group is much lower [81].