Bruno et al.[5] proposed to divide 17p13.3 microduplications in two different classes: class I microduplications involving YWHAE but not PAFAH1B1 showing a phenotype characterized by learning difficulties and/or autism with or without other congenital abnormalities; class II microduplications always harboring PAFAH1B1 that may also include the genomic region encompassing the CRK and YWHAE genes, which are associated with developmental delay, psychomotor delay, and associated hypotonia. The gene discussed is CRK; the disease is Global developmental delay.