Y RNAs are small noncoding RNAs that were originally identified as the RNA component of soluble ribonucleoproteins (RNPs) termed Ro RNPs. Ro RNPs are detected by autoimmune sera of patients suffering from rheumatic diseases, such as from systemic lupus erythematosus (MIM 152700) and Sjogren syndrome (MIM 270200). Ro RNPs consist of a Y RNA that is associated with the autoimmune antigen proteins Ro60 (TROVE2; MIM 600063) and La (SSB; MIM 109090), as well as other proteins. Four human Y RNAs have been identified: Y1, Y3 (RNY3; MIM 601822), Y4 (RNY4; MIM 601823), and Y5 (RNY5; MIM 601824). (Y2 is a truncated form of Y1.) Y RNAs are transcribed by RNA polymerase III and range in size from 83 to 112 nucleotides. They appear to have a functional role in chromosomal DNA replication (Christov et al., 2006 (PubMed 16943439)).(supplied by OMIM)