Clinical Analysis And Genetic Detection Of Hereditary Neuropathy With Liability To Pressure Palsies

Objective To conclude the clinical characters of patients with hereditary neuropathywith liability to pressure palsies (HNPP), and detect their gene mutations. Tointroduce the apply of multiplex ligation-dependent probe amplification (MLPA)assays in the genetic diagnosis in HNPP patients. Methods After collecting clinicalcharacters and DNA examples of14clinically suspected HNPP patients, copynumbers of the exons in PMP22gene、TEKT3gene and COX10gene were analyzedby MLPA in these HNPP patients and5normal controls. MLPA negative patientswere detected point mutation in exon2-5of PMP22gene by direct sequencing.Results In our study,12HNPP patients were genetically confirmed among14clinically suspected HNPP patients. Clinical symptoms varied in these12geneticallyconfirmed HNPP patients and electrophysiological examinations were performed in11cases of them. In the electrophysiology, distal motor latency was prolonged in10cases (90.9%); diffuse sensory never conduction slowing was found in10cases(90.9%); ulnar motor conduction in the above-below elbow segment was reduced in10cases (90.9%). Among the14clinically suspected HNPP patients,12wereidentified to have deletion mutations according to their reduced peak area of PMP22gene, TEKT3gene and COX10gene compared with that of normal controls.2patients with normal peak area of PMP22gene, TEKT3gene and COX10geneshowed no deletion of these genes and had no point mutation in exon2-5in PMP22 gene. Conclusions (1) HNPP has a high clinical variability, and its characteristicelectrophysiological features are prolonged distal motor latency, diffuse slowingsensory never conduction and reduced ulnar motor conduction in the above-belowelbow segment.(2) In our study,85.7%cases are found1.5Mb deletion in17p11.2region. Neither small deletion in PMP22gene nor point mutation in encoded exons ofPMP22gene is found.(3) MLPA assays can detect the copy number of genes inHNPP region through semi-quantitative analysis in a rapid, accurate way, which maybe utilized widely in the genetic diagnosis among HNPP patients.