DROSHA and 22q11.2 deletion syndrome: MicroRNA(miRNA) is transcribed by RNA polymerase II (Pol II), then cleaved by DGCR8/DROSHA (DiGeorge syndrome critical region gene 8 / Drosha Ribonuclease III) to produce a hairpin structured precursor with around 70 nucleotide (nt) in length, which is then exported to cytoplasm by exportin 514.