Lithium is the most frequently prescribed medication for adult BD, however there are differences concerning its use in children and adolescents across these guidelines: AACAP and CABF recommend lithium as a first-line agent in the long-term treatment of BD in children and adolescents, whereas NICE recommends an atypical antipsychotic with fewer adverse effects such as weight gain and elevated prolactin. This evidence concerns the gene PRL and Behcet disease.