A novel mutation in collagen transport protein, MIA3 gene, detected in a patient with clinical symptoms of Ehlers-Danlos hypermobile syndrome

Background. Collagen, the most abundant human protein, is a significant component of the extracellular matrix (ECM) in tissues and organs like skin, bone, ligaments, and tendons. Collagen secretion is a complex, multistage process involving many molecules. A protein playing one of the main functions in this process is TANGO1 encoded by MIA3 gene. In the hypermobile type of Ehlers-Danlos syndrome (hEDS), one of the most common collagenopathies with no known genetic background, disrupted secretion of many molecules (including collagen) was observed. Objectives. The aim of this study was the evaluation of the MIA3 gene role in hEDS patients. Materials and methods. One hundred patients with clinically diagnosed hEDS and negative next-generation sequencing (NGS) testing for connective tissue disorder (e.g. Ehlers-Danlos syndrome, osteogenesis imperfect (OI), Marfan syndrome, and others) were tested for molecular changes in the MIA3 gene. Results. Among the 100 tested patients, 14 single structural changes in the MIA3 gene were detected. Thirteen were missense benign or likely benign, while 1 variant (c.567dup, p.Leu1880ThrfsTer6) was truncating the TANGO1 protein. Conclusions. We suppose that the presence of truncating variant (c.5637dup) in the MIA3 gene and disrupted secretion of connective tissue protein may be one of the pathogenic mechanisms of clinical symptoms present in the tested patient, but these findings require a more comprehensive multidimensional investigation.