The patient 3, a 12-year-old boy with isolated GDD/ID, presented as a particularity a pathogenic 22q11.1-q11.21 duplication of 1.5 Mb (cat eye syndrome) associated to a pathogenic Xq27.1-q27.3 duplication of 7.4 Mb duplication, the last one including more OMIM genes, SOX3 being a known morbid OMIM gene, coding for a transcription factor implicated in neurodevelopment, which is associated with X-linked intellectual disability and panhypopituitarism or growth hormone deficiency. This evidence concerns the gene SOX3 and X-linked intellectual disability.