Human growth is a complex process and discriminating healthy tall children from those affected by acro-gigantism due to underlying diseases, either related to genetic (FIPA, and MEN1, more rarely CCS, MAS, 3PAs, MAX-associated tumours, NF1, and the recent PAM variants), or endocrine alterations (hyperthyroidism, obesity), is a compelling challenge. The gene discussed is NF1; the disease is hyperthyroidism.