The Study Of TTR Gly83Arg Mutation In A Chinese Family With Familial Amyloid Polyneuropathy

Objective:1. To analyze clinical and genetic features of a pedigree named GZ001withfamilial amyloid polyneuropathy in Guizhou province.2. To study the relation between the diseases and transthyretin(TTR), and to findthe locus and type of TTR gene mutation.Methods:1. All27subjects (12affected individuals and15unaffected individuals)underwent ocular examinations, including best correct visual acuity (BCVA),intraocular pressure (IOP) measurements, Schirmer test, slitlamp examination,three-mirror lens and fundoscopic examinations. In addition, ocular ultrasonographyand ultrasound biomicroscopy (UBM) were performed in patients IV:4, IV:6andIV:8.Additional tests were performed,including electromyography, cardiovascularmagnetic resonance (CMR) with gadolinium enhancement.2. Vitreous specimens were obtained during vitrectomies from patients IV:4andIV:6. were performed Congo red staining and Immunohistochemical examination.3. Genomic DNA were extracted from8ml peripheral blood of27subjects. Fourexons of TTR genes were amplified by polymerase chain reaction (PCR) and Sangersequencing. Subsequently, candidate mutations were validated in100normal unaffectedindividuals using Sanger Sequencing.Results:1. There are13surviving patients in the family with85members of fivegenerations, including7male and6female. The pattern of inheritance was consistentwith autosomal dominant.2. All of the12affected individuals had vitreous opacities,4affected individualswas diagnosed secondary open angle glaucoma in both eyes.10affected individuals had peripheral neuropathy. Of all subjects in the study, only patient IV:6had evidenceof cardiac amyloidosis.3. Vitreous specimens from two affected individuals (IV:4and IV:6) stainedpositive with Congo red and showed apple-green birefringence under polarized lightwith widespread deposition of amyloid in the vitreous. Positive immunohistochemicalstaining of TTR in the vitreous samples confirmed the presence of TTR proteins in thevitreous.4. Sequence analysis of TTR revealed a heterozygous missense mutation in exon3(c.307C>G) in the12affected patients as well as3asymptomatic individuals whoseage is within12-23. This mutation (c.307C>G) resulted in a transition in the codingsequence, changing the GGC codon for glycine to a CGC codon for arginine(Gly83Arg). This mutation was absent in100unrelated normal controls.Conclusion:1.. The family named GZ001is a feasures with familial amyloid polyneuropathy.Vitreous opacities is the initial symptom. Ocular impairment and peripheral sensoryneuropathy are the predominant clinical features.2. The TTR Gly83Arg was the pathogenetic gene mutation in the family, and thismutation are found only in Chinese.