Although the 2q23.1 locus contains several genes associated with genetic disorders such as ORC4, KIF5C, MMADHC, NEM2, and CACNB4, extensive analysis of the alignment of deleted regions in patients has identified MBD5 as the only gene included in the smallest region of overlap, suggesting that genetic alterations in this gene cause the primary features of 2q23.1 microdeletion syndrome. The gene discussed is ORC4; the disease is hereditary disease.