However, we detected a novel, highly conserved, and heterozygous missense variant in the KMT2D gene (c.3976C>T, R1326W), which was interpreted as a pathogenic variant within this analysis and might be causative in this particular case of a Kabuki syndrome with predominantly transient, congenital hyperinsulinism [17,18]. Here, KMT2D is linked to congenital isolated hyperinsulinism.