Recent discoveries by the UDN provided key insights into phenotypic expansion of NR5A1 in human sex determination (Bashamboo et al. 2016), ASXL2 and Shashi-Pena syndrome (MIM# 617190) (Shashi et al. 2016), and EBF3 and hypotoia, ataxia and delayed development syndrome (MIM# 617330) (Chao et al. 2017a), a gene discovery that was also made simultaneously by the CMG and the Deciphering Developmental Disorders Study (DDDS) (Harms et al. 2017; Sleven et al. 2017). The gene discussed is EBF3; the disease is cerebellar ataxia.