KCNB1 and Global developmental delay: The second one was a heterozygous missense c.367G>A (p.G123S) variant in the KCNB1 (potassium channel, voltage-gated, Shab-related subfamily, member 1) gene (not listed in gnomAD); KCNB1-deficiency is associated with the autosomal dominant DEE26 and includes variable types of seizures late in infancy or in the first years of life, developmental delay with ID, poor speech, and behavioral abnormalities (for details, see OMIM 616056).