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 TTR gene. The destabilized mutant form of the transport protein transthyretin (TTR) leads to the extracellular deposition of amyloid fibrils. Materials and Methods: A 65-year-old female patient with suspected clinical diagnosis of ATTR was referred for genetic testing for pathogenic variants in the TTR gene after physical, neurological and cardiac testing. Results: 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 TTR gene NM_000371.4(TTR): c.258A>C, p.(Glu86Asp). This variant in the TTR gene is classified as pathogenic in accordance with ACMG/AMP for the interpretation of variants. Conclusions: The presented case of a very rare pathogenic variant in the TTR gene displays the valuable role of genetic testing on the way to clarifying a diagnosis.