Novel Pathogenic Variant c.258A>C, p.(Glu86Asp) in the TTR Gene in a Bulgarian Patient with Hereditary Transthyretin Amyloidosis

Hereditary transthyretin amyloidosis (ATTRv) is an autosomal dominant disorder caused by pathogenic variants in the <i>TTR</i> gene. The destabilized mutant form of the transport protein transthyretin (TTR) leads to the extracellular deposition of amyloid fibrils. <b>Materials and Methods:</b> A 65-year-old female patient with suspected clinical diagnosis of ATTR was referred for genetic testing for pathogenic variants in the <i>TTR</i> gene after physical, neurological and cardiac testing. <b>Results:</b> The patient had had cardiac dysfunction, atrial fibrillation and supraventricular tachycardia for around 10 years before the suspected and confirmed cardiac amyloidosis. The molecular genetic testing showed a heterozygous pathogenic variant in exon 3 of the <i>TTR</i> gene NM_000371.4(TTR): c.258A>C, p.(Glu86Asp). This variant in the <i>TTR</i> gene is classified as pathogenic in accordance with ACMG/AMP for the interpretation of variants. <b>Conclusions:</b> The presented case of a very rare pathogenic variant in the <i>TTR</i> gene displays the valuable role of genetic testing on the way to clarifying a diagnosis.