SCA-12 Spinocerebellar Ataxia Type 12 Test
SCA-12 Spinocerebellar Ataxia Type 12 Test
Ataxias is a condition where different aspects like muscle movement, posture, gait, coordination, and speech are affected. Abnormal repeats in the DNA sequences coding for the building blocks of proteins, called amino acids, create misfolded proteins. When these misfolded proteins affect the cerebellum, which is a part of the brain responsible for muscle movement and coordination, and the spinal cord, this type of ataxia is called the spinocerebellar ataxia (SCA). Different patterns of repeats in the DNA sequences, present in different locations in certain genes, result in different types of SCA (called subtypes), for example SCA 1, 2, 3, 6, 7, 12 etc. One of these subtypes, is the SCA-12, which is a rare condition, where hand tremor and gait issues are more dominant. The SCA-12 test is done to check for the pattern of DNA sequence repeats associated with this subtype.
What is the SCA-12 Test Used For?
SCA-12 test is used for finding if a person has this particular subtype of SCA. It is usually recommended after testing for more common subtypes like SCA-1, 2, 3, 6, 7, also known as the SCA Comprehensive Panel.
Symptoms of Spinocerebellar Ataxia Type 12
This test is recommended for people who are at the risk of SCA-12. Some of the symptoms of SCA-12 are
Worsening gait and posture
Hand Tremors (slower tremors, but more movement)
Speaking difficulty due to tongue muscle weakness
Psychiatric Issues
Bradykinesia or slow movement
Increased reflex response of the muscles
Muscle or eye twitching
Preparation for Test
Before the test, let your general physician know of any medication, supplements or treatments that you are taking or currently undergoing. No other special preparations are required for this test.
Interpretation of Test Results
DNA is composed of building blocks called nucleotides, and these can be of four types (A: Adenine, T: Thymine, C: Cytosine, G: Guanine). Depending on the combination of these nucleotides, different amino acids can be coded, forming proteins. The SCA-12 test is performed by amplifying the portion of the gene, called PPP2R2B known to have the repeated sequences of CAG, for SCA-12.
Normal Values (Negative for the SCA-12): Reference values are normal values of the CAG repeats observed in the PPP2R2B gene, associated with SCA-12. In this case having CAG repeats within 4-32, would likely mean you do not have the SCA-12.
Abnormal Values (Positive for the SCA-12): Values outside of the reference range (Abnormal Values) with CAG repeats more than 43, may indicate that you are likely to have the SCA-12. This cut-off value may vary depending on the diagnostic laboratory and the region where it is being tested.
FAQs
How is the sample collected for the SCA-12 test?
A blood sample is collected from a vein in your arm.
What is the turnaround time (TAT) for SCA-12 test?
The tests results should come within 1-2 days after the sample is taken. This time would depend on the diagnostic laboratory that has taken the sample for analysis.
What is the treatment for this subtype of SCA?
SCA-12 does not have a cure. Symptoms are managed by medications like beta blockers, helps in decreasing the tremors; medications for psychiatric symptoms, and other medications for decreasing pain and muscle issues associated with SCA-12. Physiotherapy and psychological interventions can also help improve motor learning and control, posture etc. As, SCA-12 is a rare condition, studies are being conducted to discover more effective treatments for this condition.
Who is more likely to have this subtype?
As SCA-12 is a very rare condition with few reported cases, no specific patterns have been observed. Men and women have similar chances to have this condition, with symptoms being observed as early as 34-37 years of age. It is more common to observe the symptoms at the age of 40s and 50s. More cases have been reported in the northern part of India.
Does this disease get worse with time??
Usually with time, the symptoms of this disease may worsen.SCA-12 is known to have a slower progression compared to other subtypes of this condition.
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