Ornithine Transcarbamylase Deficiency (OTCD) (OMIM# 311250), the most common of urea cycle defects (UCDs) with an estimated incidence of 1 in 66.000–70.000 [1, 2], is caused by mutations in OTC gene mapping on Xp11.4 [3, 4]. Here, OTC is linked to ornithine carbamoyltransferase deficiency.