Spinocerebellar ataxia type 17 (type 4-like Huntington's Disease ... -HLD4-) Spinocerebellar Ataxia Type 17 (Huntington disease-like 4 -HDL4-) - Gen TBP
Spinocerebellar ataxia type 17 (SCA17), also known as Huntington's disease-like type 4 (HDL4: Huntington Disease-like type 4), is a disorder resembling Huntington's disease. They described four syndromes HDL (HDL1, HDL2, HDL3 and HDL4). In all progressive brain disorders, which are characterized by the manifestation of uncontrolled movements, emotional problems and loss of reasoning, that occur in people with the characteristics of Huntington's disease occur, but do not have their own mutations of Huntington's disease .
Spinocerebellar ataxia type 17 (HDL4), usually manifests at the beginning of adulthood, or half of it, although sometimes appears before. Early symptoms include irritability, emotional problems, involuntary movements, poor motor coordination and learning or decision - making. As the disease progresses, abnormal movements become more pronounced and can present problems in gait, speech or swallowing. Survival from the onset of symptoms, may be a few years to over a decade.
In spinocerebellar ataxia type 17 (HDL4) it is affected TBP gene, located on the long arm of chromosome 6 (6q27). The TBP gene encoding the binding protein TATA, important for the development of normal brain function box. This protein is active in cells and tissues throughout the body, where it plays an essential role in regulating the activity of most genes. The binding protein TATA binds to a particular DNA sequence known as the TATA box. This sequence occurs in a regulatory region of DNA near the beginning of many genes. Once the protein binds to the TATA box near a gene, it acts as a reference point to indicate where other enzymes should begin to transcribe the gene. A region of the TBP gene containing a particular DNA segment, known as a CAG trinucleotide repeat / CAA. This segment consists of a series of three nucleotides that appear several times in a sequence. Typically, the segment CAG / CAA repeats of 25 to 42 times within the gene.
A particular mutation in the TBP gene increases the length of DNA repeated segment of these genes, leading to abnormal protein TBP. People with 43 to 48 repetitions CAG / CAA may or may not show signs and symptoms, while people with more than 49 repetitions almost always develop the disease. This abnormal protein occurs in neurons and alter their function. Dysfunction or death of neurons in some brain areas, because the signs and symptoms of all HDL syndromes, including cerebellar ataxia type 17.
Spinocerebellar ataxia type 17 (SCA17) has an autosomal dominant inheritance, ie, an altered copy in each cell causes disease. Affected inherit the mutation from one parent affected. As is transmitted to offspring, can increase in length DNA fragment repeated, making signs and symptoms (early) fester.
Tests in IVAMI: in IVAMI perform detection of mutations associated conataxia spinocerebellar type 17 (SCA17), by complete PCR amplification of the exons of the TBP gene, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).