Mutations of key ribosome components underlying ribosomopathies. The DKC1 gene encoding dyskerin (rRNA pseudouridine synthase) is frequently mutated in X-DC. The SBDS gene encodes the SDBS protein and is found to be mutated in SDS. RP genes encoding ribosomal proteins belonging to both the large and small ribosomal subunits are found to be mutated in DBA.