Focusing on the autosomal dominant form of IGHD, type II (IGHD II) is mainly caused by mutations within the first six bp of intervening sequences 3 (5’IVS−3) (8, 62, 63, 64, 65, 66), which result in a missplicing at the mRNA level and the subsequent loss of E3, producing a 17.5−kDa hGH isoform (8, 65). This evidence concerns the gene GH1 and isolated growth hormone deficiency type II.