In family 1, we also identified an additional homozygous missense variant, c.425 C > T (p.Thr142Met) in SLC13A5 (NM_177550), a gene located ~44 kb upstream of KIAA0753. This mutation has been reported previously to cause autosomal recessive early infantile epileptic encephalopathy 25 (EIEE25 [MIM:615905]), a condition associated with seizures, developmental disability and teeth hypoplasia21,22. This evidence concerns the gene SLC13A5 and developmental disability.