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

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.