Genetic screening of three Pakistani ID families in the current study resulted in the identification of three novel plausible ID genes, KMT2B, ZNF589 and HHAT. The phenotype of the three affected members of family MRQ14 had Kleefstra syndrome-like phenotype (clinical details are described in clinical features section), which is characterized by facial dysmorphism, hypotonia and mild to severe ID (Figure 2). This evidence concerns the gene HHAT and Kleefstra syndrome.