A rearrangement of the CDD gene at the 5' UTR produces two types of transcripts that contain a natural antisense region.

In order to study the regulatory region for transcription, the genomic DNA of the human CDD gene was cloned and analyzed. In contrast to previously reported CDD cDNA sequence, the sequence of the isolated genomic clone was rearranged at the 5' untranslated region (UTR) by a 30 bp inversion and a 57 bp insertion. Polymerase chain reaction (PCR) of chromosomal DNA and mRNA, and sequencing analysis of the PCR products revealed that sequences corresponding to both the genomic clone and the cDNA clone were present in the chromosomal DNA and were also transcribed into mRNA. Because of the 30 base inversion, the two types of CDD transcripts contain antisense sequences in their 5' UTR. Their role in the regulation of CDD expression is discussed.