# Coronoidectomy for Alleviating Restricted Mouth Opening in Masticatory Muscle Tendon-Aponeurosis Hyperplasia: Integration With Genetic Mutation Analysis

## TL;DR

A new genetic mutation linked to a rare jaw condition is identified, helping distinguish it from similar disorders.

## Contribution

A novel SYNE1 missense mutation is reported in a patient with masticatory muscle tendon-aponeurosis hyperplasia.

## Key findings

- A heterozygous SYNE1 missense mutation (c.26359A>G, p.Met8787Val) was identified in a patient with MMTAH.
- The mutation is located in Exon 146 and is predicted to be pathogenic.
- Genetic screening is emphasized for accurate diagnosis of atypical MMTAH cases.

## Abstract

Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is often misdiagnosed as temporomandibular joint disorders, hypertrophic masticatory muscles, or congenital maxillomandibular dysplasia due to overlapping clinical manifestations. This case study is aimed at elucidating a novel genetic association in MMTAH by reporting a patient with pathognomonic features, including chronic limited mouth opening, bilateral coronoid process elongation, tendon hyperplasia in the masseter and temporalis muscles, and concomitant fatty degeneration. Crucially, whole-exome sequencing of peripheral blood identified a heterozygous SYNE1 missense mutation (NM_182961.4:c.26359A>G, p.Met8787Val) in the proband. This variant, located in Exon 146 (Chr6:152122471), is an unreported variant at this locus and predicted pathogenic by in silico tools, suggesting its potential role in MMTAH pathogenesis. The study highlights the importance of genetic screening in atypical presentations to refine diagnosis and understand disease etiology.