RARA and acute promyelocytic leukemia: Among others, a short insertion of nine nucleotides (CCCCCAGTT) of unknown origin has been reported in a PML-RARA fusion between PML exon 4 and part of the exon 1 of RARA2. This was the first time that a fusion transcript involving the alternative isoform of RARA was found in an APL patient [82].