Correlation between mutated genes and forearm deformity in patients with multiple osteochondroma

Area of Science:

• Genetics
• Orthopedics
• Medical Research

Background:

• Multiple osteochondromas (MO) is a genetic disorder.
• Exostosin-1 (EXT1) and exostosin-2 (EXT2) genes are implicated in MO pathogenesis.
• Forearm deformities are a common manifestation of MO.

Purpose of the Study:

• To investigate the correlation between forearm deformity and mutations in EXT1 and EXT2 genes.
• To compare the severity of forearm deformities in Japanese patients with MO based on their genetic mutation type (EXT1 vs. EXT2).

Main Methods:

• Evaluated 112 patients from 71 families with MO.
• Selected 28 patients with gross forearm deformities for detailed radiographic analysis.
• Measured radial articular angle (RAA), ulna variance (UV), carpal slip (CS), and percentage of radial bowing (%RB) to compare mutation groups.

Main Results:

• Mutations in EXT1 and EXT2 were identified in 78.6% and 11.4% of the analyzed patients, respectively.
• Patients with EXT1 mutations showed significantly greater carpal slip (CS) compared to those with EXT2 mutations.
• No significant differences in RAA, UV, or %RB were observed between EXT1 and EXT2 mutation groups or between missense and other mutation types.

Conclusions:

• Mutant EXT1 is associated with more severe ulnar drift deformities (indicated by greater CS) than mutant EXT2 in Japanese patients with MO.
• These findings highlight the differential impact of EXT1 and EXT2 mutations on skeletal deformity severity in MO.