Case Report: Diagnostic odyssey in rare diseases: when genetic variants are misinterpreted

Introduction: gene at age 5, despite the patient never fulfilling the established clinical diagnostic criteria for the disease. Methods: c.5544_5548del, p.(D1848Efs*60) variant. Results: are associated with thoracic aortic aneurysms and dissections, loss-of-function variants are linked to autosomal recessive Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome (MMIHS). As a heterozygous carrier of a loss-of-function variant, the patient is asymptomatic for MMIHS and definitively does not have MFS. Currently, the 11-year-old child is progressing favorably without any notable pathology. Conclusions: This case exposes the entire diagnostic odyssey suffered by the patient's family and highlights three fundamental systemic errors: the critical delay in genetic counseling, the over-interpretation of NGS data by external laboratories lacking phenotypic context, and the health system's inefficiency in integrating clinical geneticists. Overcoming these barriers is essential for the true implementation of personalized precision medicine.