A rare variant in the TTR gene (p.E112K) is associated with systemic amyloidosis and a new symptom – skin hyperemia in response to ethanol intake: family segregation analysis, literature review, and a clinical case. Case report

Transthyretin amyloidosis (ATTR-amyloidosis) is a systemic disorder associated with extracellular deposition in the tissues and organs of amyloid fibrils, transthyretin-containing insoluble protein-polysaccharide complexes. The change in transthyretin conformation, leading to its destabilization and amyloidogenicity, can be acquired (wild type, ATTRwt) and hereditary due to mutations in the TTR gene (variant, ATTRv) [1, 2]. Hereditary ATTR-amyloidosis has an earlier onset and greater phenotypic diversity. The age of the manifestation, the predominant phenotype, and the prognosis are often determined by the genetic variant. To date, more than 140 variants in the TTR gene have been identified; however, most of them are described in single patients and do not have clear evidence of pathogenicity. The prospects of a new pathogenetic treatment of ATTR-amyloidosis [3], especially effective in the early stages of the disease, increases the relevance of timely diagnosis, which is challenging due to physicians' lack of awareness. This article presents a clinical case of ATTRv-amyloidosis associated with a rare pathogenic variant in the TTR gene and a newly described skin symptom. This article is a literature review.