RNU4ATAC: RNU4ATAC is a gene that encodes the small nuclear RNA (snRNA) U4atac, which is a component of the minor spliceosome [PMC4772811]. Mutations in splicing proteins have been linked to primordial dwarfism, and specifically, mutations in RNU4ATAC have been found to cause MOPDI [PMC4045235]. MOPD1 is a form of primordial dwarfism that results from biallelic mutations in the RNU4ATAC gene [PMC4772811]. The minor spliceosome, which includes U4atac, is responsible for splicing specific introns that are not recognized by the major spliceosome [PMC4045235]. Mutations in RNU4ATAC disrupt the normal splicing process and lead to abnormal development and growth [PMC4772811]. The identification of RNU4ATAC mutations as a cause of MOPDI has provided insights into the molecular mechanisms underlying primordial dwarfism and has expanded our understanding of the role of splicing in development [PMC4045235]. Further research is needed to fully elucidate how mutations in RNU4ATAC specifically contribute to the pathogenesis of MOPDI and how they affect splicing processes [PMC4772811].