RNU4-2 and neurodevelopmental disorder with hypotonia, brain anomalies, distinctive facies, and absent language: These groups comprised of three distinct variants in two ribozyme genes, 15 variants in 12 snoRNA genes, and 86 variants in 18 snRNA genes (Fig. 1d and Supplementary Table 3), including five known recessive disease genes (Supplementary Table 4) and dominant ReNU syndrome (OMIM 620851) associated RNU4-2 (n = 36)9,10.