Beta1 catenin, also known as beta-catenin, is a protein encoded in humans by the CTNNB1 gene. It’s a dual-function protein that is a part of processes that regulate and coordinate cell-to-cell adhesion and gene transcription. It’s also involved in cell signaling where other proteins attach to beta-catenin which triggers the movement of proteins into cell nuclei and this allows the proteins to control gene expression. The specific signaling pathway that it’s involved in is the Wnt pathway promotes growth and division of cells and also any specialized functions the cell will have. The Wnt pathway plays a big role in development before birth and maintaining stem cells in adults.
Mutations of this gene are associated with liver cell carcinoma, bowel carcinoma, lung cancer, malignant breast cancer, ovarian cancer, and endometrium. Changes in localization and expression levels of beta-catenin were related to various forms of heart disease, including myocardial patients. One of the biggest disorders related to beta-catenin is CTNNB1 syndrome.
CTNNB1 syndrome is a serious neuronal disorder due to the destruction of a chromosome in the CTNNB1 gene. This is a recently discovered condition related to delayed development, intellectual disability and language delay. Since the first case of CTNNB1 syndrome, registered in 2012, there have been many more diagnostic cases. CTNNB1 syndrome affects 1 in 50,000 children worldwide. It is inherited in an autosomal dominant manner, meaning that only one copy of the genetic variation is required to express the observed phenotype. CTNNB1 syndrome occurs when one of two copies of the CTNNB1 gene loses its normal function. CTNNB1 being so important in brain development and maturation, it makes sense that this syndrome is mainly associated with developmental and intellectual disabilities. Many children show motor delays in being able to sit or walk unsupported, and even that occurs months after the typical milestone. Patient speech is also delayed and varies among children, but most are capable of understanding better than speaking.
Symptoms of this disorder include low muscle tone, small head size, vision problems, heart issues, and abnormal brain scans. Babies born with low muscle tone have motor delays and feeding problems. They may also have spasticity in their limbs. A small head size, or microencephaly, is another indication of this syndrome due to lack of development of the brain. A lot of people may also have eye problems which are quite varied and range from nearsightedness to retinal atrophy. Brain scan abnormalities may show odd wrinkles on the brain, dilated ventricles, an underdeveloped corpus callosum, etc. There is also a recently discovered association between this syndrome and congenital heart defects.
Currently, as it is a rare and recently discovered disease, there are not many treatments underway but research is actively being done. One treatment method, however, is gene therapy. It’s a way to directly target the CTNNB1 gene and replace the patient’s copy with a new, working copy. More specific information about that can be found discussed with a primary care physician who may refer you to more specialized practitioners. There are also many organizations and foundations to support, like the CTNNB1 Foundation.
Sources:
“What is CTNNB1 syndrome?” CTNNB1 Foundation, https://ctnnb1-foundation.org/ctnnb1-syndrome/
“CTNNB1 gene.” MedlinePlus, https://medlineplus.gov/genetics/gene/ctnnb1/#conditions
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