Characteristics Of Symptoms And TTR Mutations In Chinese FAP Patients

Familial amyloid polyneuropathy (FAP) is an autosomal dominant inheriteddisease caused by the mutation of TTR gene. Its clinical features are similar with thatof Chacot-Marie-Tooth (CMT). This study is to investigate the clinical features andthe genetic characteristics of TTR gene in Chinese Han FAP patients.Methods: The5clinical diagnosed FAP patients and2family members withoutsymptoms were from3different families and included consecutively from the geneticclinic of our hospital. We retrospected the clinical materials of the5patients. Thepolymerase chain reaction followed by direct DNA sequencing of the4exons of TTRgene was performed in the7subjects above and37CMT patients with familyhistories from different families.Results:5clinically diagnosed FAP patients presented impaired sensations thenmuscular atrophy in both lower limbs, which developed to the upper limbs gradually.2of them had postural hypotension. The electromyogram results of3patients fromdifferent families showed poly peripheral nerves damaging，with the sensory andmotorial nerves affected and axon damaged. The nerve biopsy of2patients indicatedamyloid deposits. The mutation of Tyr116Ser、 Ala36ProandThr49Ala/delGACTTCTCC (the deletion of9bp following2bp next to thetermination codon). The3mutations were heterozygous mutations，which located onexon2,3and4. These mutations were all reported but not in Chinese FAP patients.Otherwise, in the33CMT patients, there were only1deletion mentioned above and1synonymous mutation of Thr119Thr.Conclusion: FAP disease in China is rare, but it is still needed to pay attention todistinguish with other peripheral neuropathy. The nerve biopsy and genetic testing isof help to the diagnosis.