Hereditary ATTR Amyloidosis in Austria: Prevalence and Epidemiological Hot Spots.

BACKGROUND: Hereditary transthyretin amyloidosis (hATTR) is an autosomal dominantly inherited disorder caused by an accumulation of amyloid fibrils in tissues due to mutations in the transthyretin (TTR) gene. The prevalence of hATTR is still unclear and likely underestimated in many countries. In order to apply new therapies in a targeted manner, early diagnosis and knowledge of phenotype-genotype correlations are mandatory. This study aimed to assess the prevalence and phenotypic spectrum of hATTR in Austria. METHODS: Within the period of 2014-2019, patients with ATTR-associated cardiomyopathy and/or unexplained progressive polyneuropathies were screened for mutations in the TTR gene. RESULTS: We identified 43 cases from 22 families carrying 10 different TTR missense mutations and confirmed two mutational hot spots at c.323A>G (p.His108Arg) and c.337G>C (p.Val113Leu). Two further patients with late onset ATTR carried TTR variants of unknown significance. The majority of patients initially presented with heart failure symptoms that were subsequently accompanied by progressive polyneuropathy in most cases. A total of 55% had a history of carpal tunnel syndrome before the onset of other organ manifestations. CONCLUSIONS: Our study underlined the relevance of hATTR in the pathogenesis of amyloid-driven cardiomyopathy and axonal polyneuropathy and indicated considerable genetic heterogeneity of this disease in the Austrian population. The estimated prevalence of hATTR in Austria based on this study is 1:200,000 but a potentially higher number of unknown cases must be taken into account. With respect to new therapeutic approaches, we strongly propose genetic testing of the TTR gene in an extended cohort of patients with unexplained heart failure and progressive polyneuropathy.

First case study of periodic hypokalemic thyreotoxic paresis with partial respiratory insufficiency and concomitant sinus bradycardia.

This report describes the case of a 29-year-old Chechen refugee with periodic hypokalemic thyreotoxic tetraparesis (PHTP). Besides a partial respiratory insufficiency, the patient was also presented with sinus bradycardia. Medical literature describes several cases of thyreotoxicosis in combination with bradycardia. For the first time, we were able to observe a case of PHTP in combination with sinus bradycardia. PHTP is rarely seen in central Europe. In this case establishing a final diagnosis was difficult because of the concomitant presence of bradycardia and Graves' disease.