CNBP

The CNBP gene provides instructions for making a protein called CCHC-type zinc finger, nucleic acid binding protein. This protein is found in many of the body's tissues, but is most abundant in the heart and in muscles used for movement (skeletal muscles). Although the exact function of this protein remains unclear, it probably helps regulate genes involved in the production and use of cholesterol. The protein has seven regions, called zinc finger domains, which are thought to attach (bind) to specific sites on messenger RNA (a molecule similar to DNA that forms a blueprint for making proteins).

One region of the CNBP gene has a particular repeating sequence of four DNA building blocks (nucleotides), written as CCTG. The CCTG sequence is usually repeated fewer than 26 times within the gene and is called a tetranucleotide repeat.

myotonic dystrophy - caused by mutations in the CNBP gene

Type 2 myotonic dystrophy is caused by an expansion of the CCTG tetranucleotide repeat in the CNBP gene. This condition occurs when the CCTG segment is abnormally repeated 75 to more than 11,000 times.

Researchers have found that the mutated CNBP gene produces an altered messenger RNA, which interacts with certain proteins to form clumps within the cell. The abnormal clumps interfere with the production of many other proteins. These changes prevent cells in muscles and other tissues from functioning normally, leading to the signs and symptoms of type 2 myotonic dystrophy.