Japanese 17q12 Deletion Syndrome with Complex Clinical Manifestations

17q12 deletion syndrome is a rare chromosomal anomaly with variable phenotypes, caused by the heterozygous deletion of chromosome 17q12. We herein report a 35-year-old Japanese patient with chromosomal 17q12 deletion syndrome identified by de novo deletion of the 1.46 Mb segment at the 17q12 band by genetic analyses. He exhibited a wide range of phenotypes, such as maturity-onset diabetes of the young (MODY) type 5, structural or functional abnormalities of the kidney, liver, and pancreas; facial dysmorphic features, electrolyte disorders; keratoconus, and acquired perforating dermatosis. This case report provides valuable resources concerning the clinical spectrum of rare 17q12 deletion syndrome.