PAK3 and Intellectual disability: ,30,31,32,33,34,35,36,37 If these nonsense PAK3 mRNAs were to escape NMD, then the encoded truncated protein would lack its kinase domain and encode a protein consisting only of its inhibitory domain, with potential to also inhibit PAK3 heterodimeric partners such as that encoded by PAK1 (MIM: 602590), a gene for which haploinsufficiency also causes intellectual disability (MIM: 618158).93