Recurrent Mutation (p.Arg718Pro) in the COMP Gene with Clinical Heterogeneity of Pseudoachondroplasia.

Introduction: Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) are allelic and caused by mutations in the COMP gene. Other mutations in the genes MMP13, AIFM1, B3GALT6, MATN3, COL9A1, COL9A2, COL9A3, and SLC26A2 have also been associated with evidence of dysplasia in the epiphysis, metaphysis, and spine. Case Presentation: We report on the first Mexican patient diagnosed with PSACH. The diagnosis was confirmed by identifying a recurrent heterozygous mutation c.2153G>C (p.Arg718Pro) in the COMP gene using whole-exome sequencing. Discussion: The anterior spindle-shaped vertebral bodies and severe short stature are not observed in patients carrying p.Arg718Pro, identifying another amino acid site associated with clinical heterogeneity. Reporting new cases with clinical heterogeneity in terms of phenotype plays a crucial role in understanding PSACH and MED pathogenesis. The most important aspect of this presentation is providing a new perspective on a recognized clinical scenario, thus setting the standard for better genetic counseling.