| Summary: | 碩士 === 高雄醫學大學 === 醫學研究所 === 97 === Charcot-Marie-Tooth disease (CMT) is one of the most common inherited peripheral neuropathies. According to the hereditary pattern, clinical manifestations and electrophysiologic findings, CMT could be divided into many subgroups. CMT type 1 is an autosomal dominant demyelinating motor and sensory neuropathy. The most common subtype of CMT type 1 is CMT1A, which is caused by the duplication of a 1.5 Mb region containing the peripheral myelin protein 22 (PMP22) gene on chromosome 17p11.2-12. Hereditary neuropathy with liability to pressure palsies (HNPP), another autosomal dominant peripheral neuropathy, is caused by deletion of the PMP22 gene.
The diagnosis of CMT in the past was mainly dependent on clinical manifestations, family history, electrophysiologic findings and/or sural nerve biopsies. However, these methods could not give information about the underlying genetic defects, so molecular methods were developed for genetic diagnosis. Some molecular diagnostic methods have been used for the diagnosis of CMT. Some methods are accurate, but have the disadvantage of labor-intensive and time-consuming. Some methods are relatively expensive and require specific equipments. We performed real-time quantitative PCR using SYBR Green I dye with our own designed primers for the diagnosis of CMT1A and HNPP. We use comparative threshold cycle method to calculate the estimated PMP22 gene copy number ratio. The estimated PMP22 gene copy number ratio is 1.47 for CMT1A, 0.52 for HNPP and 0.99 for control. Our method could separate the three groups of samples accurately without overlapping.
Real-time quantitative PCR using SYBR Green I dye is a sensitive, specific, accurate and reproducible method for the diagnosis of PMP22 gene duplication or deletion. By this method, we could make diagnosis for patients with CMT1A, HNPP, and other types of hereditary neuropathy and could provide them useful information about medical resources and therapeutic developments of the disease. For asymptomatic and high risk families, this method could also provide genetic screening and counseling.
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