SBDS, ribosome maturation factor
The SBDS gene provides instructions for making a protein that is critical for building ribosomes. Ribosomes are cellular structures that process the cell's genetic instructions to create proteins. Each ribosome is made up of two parts (subunits) called the large subunit and the small subunit. The SBDS protein helps prepare the large subunit so it can assemble into the ribosome by helping remove another protein (called eIF6) that blocks the interaction of the large subunit with the small subunit.
Research suggests that the SBDS protein may be involved in other cellular processes, such as ensuring proper cell division, aiding cell movement, protecting cells from stress, and processing RNA, a molecule that is a chemical cousin of DNA. More research is needed to clarify the protein's role in these processes.
More than 80 mutations in the SBDS gene have been identified in people with Shwachman-Diamond syndrome. This condition causes problems related to impaired function of the bone marrow and pancreas. Affected individuals also have skeletal abnormalities and a higher-than-average chance of developing a blood cell cancer called acute myeloid leukemia or a related bone marrow disorder called myelodysplastic syndrome.
Many of the SBDS gene mutations involved in Shwachman-Diamond syndrome result from an exchange of genetic material between the SBDS gene and a very similar, but nonfunctional, piece of DNA called a pseudogene, which is located close to the SBDS gene on chromosome 7. This type of DNA exchange is called a gene conversion. The genetic material from the pseudogene contains errors that, when introduced into the SBDS gene, disrupt the way the gene's instructions are used to make a protein.
The two most common mutations in people with Shwachman-Diamond syndrome result from exchanges between the SBDS gene and the nearby pseudogene. One of these mutations, written as 258+2T>C, changes a single DNA building block (nucleotide) in a region of the gene known as intron 2. This mutation, which is called a splice-site mutation, prevents the production of functional SBDS protein. Other splice-site mutations in the SBDS gene can also cause Shwachman-Diamond syndrome. The other common mutation, written as 183_184delTAinsCT, changes two nucleotides in the SBDS gene. This genetic change introduces a premature stop signal in the instructions for making the SBDS protein. It is unclear whether this mutation results in an abnormally shortened protein or prevents any protein from being made.
The features of Shwachman-Diamond syndrome result when mutations reduce the amount or impair the function of the SBDS protein. Researchers are unsure how a reduction of functional SBDS protein causes the condition. They suspect a shortage of SBDS protein impairs ribosome formation, which may reduce the production of other proteins and alter developmental processes. It is unclear whether disruption of other cellular functions contribute to the features of Shwachman-Diamond syndrome.
- SBDS ribosome assembly guanine nucleotide exchange factor
- SBDS, ribosome assembly guanine nucleotide exchange factor
- Shwachman-Bodian-Diamond syndrome