Abstract

Objectives

V30M in transthyretin (TTR) gene is causative for hereditary ATTRv amyloidosis (familial amyloid polyneuropathy). ATTRv amyloidosis shows a wide variation in age-at-onset (AO) between clusters, families, and among generations. We aim at identifying genetic modifiers of disease onset that may contribute to this variability in Portuguese patients by identifying other variants in TTR locus, beyond the ATTRv amyloidosis causing variant that could play a regulatory role in its expression level.

Methods

We analysed DNA samples of 330 ATTRV30M carriers (299 patients, 31 aged-asymptomatic carriers aged >40 years) from 120 families currently under follow-up. A generalised estimating equation analysis (GEE) was used to take into account non-independency of AO between relatives. An intensive in silico analysis was performed in order to understand a possible regulation of gene expression.

Results

We found 11 rare variants in the promoter, coding and intron/exon boundaries of the TTR gene associated with the onset of symptoms before and after age 40 years, namely 2 novel ones and a tandem CA-dinucleotide repeat. Furthermore, of the 4 common variants found, one was significantly associated with AO and may influence the constitutive splicing of TTR pre-mRNA. The seven ATTRV30M/V30M homozygous do not carry any of the variants identified in this study, including the common ones. In silico analysis disclosed significant alterations in the mechanism of splicing, transcription factors and miRNAs binding.

Conclusions

Variants within the promoter region may modify disease expressivity and variants in the 3’UTR can impact the efficacy of novel therapeutic interventions. Importantly, the putative mechanisms of regulation of gene expression within the TTR gene deserve to be better explored, in order to be used in the future as potential therapeutical targets.

中文翻译：

---

超越 Val30Met 转甲状腺素蛋白 (TTR)：与遗传性 ATTRv 淀粉样变性发病年龄相关的变异

摘要

目标

甲状腺素运载蛋白 ( TTR ) 基因中的 V30M 是遗传性 ATTRv 淀粉样变性（家族性淀粉样多发性神经病）的病因。ATTRv 淀粉样变性表现出在集群、家族和世代之间的发病年龄 (AO) 存在很大差异。我们的目标是通过识别TTR 基因座中的其他变体来识别可能导致葡萄牙患者这种变异性的疾病发作的遗传修饰因子，而不是导致 ATTRv 淀粉样变性的变体，这些变体可能在其表达水平中发挥调节作用。

方法

我们分析了来自目前正在随访的 120 个家庭的 330 名 ATTRV30M 携带者（299 名患者，31 名年龄 > 40 岁的老年无症状携带者）的 DNA 样本。广义估计方程分析 (GEE) 用于考虑亲属之间 AO 的非独立性。为了了解基因表达的可能调节，进行了密集的计算机分析。

结果

我们在TTR基因的启动子、编码和内含子/外显子边界中发现了 11 个罕见变异，这些变异与 40 岁前后的症状发作相关，即 2 个新变异和一个串联的 CA-二核苷酸重复序列。此外，在发现的 4 种常见变体中，一种与 AO 显着相关，并可能影响 TTR pre-mRNA 的组成型剪接。七个 ATTRV30M/V30M 纯合子不携带本研究中鉴定的任何变体，包括常见的变体。计算机分析揭示了剪接机制、转录因子和 miRNA 结合的显着变化。

结论

启动子区域内的变异可能会改变疾病的表达能力，而 3'UTR 中的变异可能会影响新型治疗干预的功效。重要的是， TTR基因内基因表达调控的推定机制值得更好地探索，以便在未来用作潜在的治疗靶点。