RNU4ATAC and Roifman syndrome: While Roifman Syndrome and MOPD1 are extremely rare, recurrent spontaneous abortions or congenital disorders with a broader phenotypic spectrum may be caused by homozygous or compound heterozygous variants altering any of the RNU4ATAC structural elements critical for splicing, with an estimated prevalence up to 1 in 30,000 pregnancies (Supplementary Note 3).