# Clinical and genetic analysis of a family with transthyretin amyloid polyneuropathy caused by a TTR Lys55Asn mutation

## TL;DR

This study examines a rare TTR gene mutation causing severe amyloid polyneuropathy with early-onset gastrointestinal issues and rapid disease progression.

## Contribution

The study provides new clinical insights into the rare TTR Lys55Asn mutation and its severe phenotype.

## Key findings

- The TTR Lys55Asn mutation causes early-onset gastrointestinal dysfunction and sensorimotor polyneuropathy.
- The mutation leads to rapid disease progression with a mean age of death at 46.13 years.
- Genetic anticipation was observed, with earlier symptom onset in successive generations.

## Abstract

transthyretin-mediated familial amyloid polyneuropathy (ATTR-PN), caused by TTR gene mutations, leads to systemic amyloid deposition and multisystem dysfunction. The c.165G > C (p.Lys55Asn) mutation is a rare variant with limited clinical data. This study investigates a family with this mutation, focusing on genotype-phenotype correlations and clinical challenges.

We conducted a detailed clinical analysis of a family with ATTR-PN, using whole exome sequencing to identify the transthyretin (TTR) mutation. Clinical data from 17 affected individuals were collected, including symptom onset, disease progression, and outcomes. Electromyography and gastric emptying studies were performed to assess peripheral nerve and gastrointestinal function.

The c.165G > C mutation was confirmed in all affected family members, presenting with early-onset gastrointestinal dysfunction and sensorimotor polyneuropathy. The mean age at onset was 39.76 ± 2.77 years, with rapid progression to death (mean age 46.13 ± 2.97 years) due to cachexia from gastrointestinal complications. Genetic anticipation was observed, with earlier onset in successive generations.

The p.Lys55Asn mutation in the TTR gene leads to a severe, rapidly progressive ATTR-PN phenotype, characterized by prominent gastrointestinal dysfunction. This study enhances understanding of the clinical spectrum associated with this rare mutation, emphasizing the need for early diagnosis and targeted management strategies.

The online version contains supplementary material available at 10.1186/s13023-025-04148-7.