MIA3 and diabetes mellitus: This is particularly noteworthy based on the recently reported role of TANGO1 in mucin export in Drosophila salivary glands and insulin secretion (Fan et al., 2017; Kang et al., 2019; Reynolds et al., 2019) Therefore, the complex phenotype of our patients, including DGI, diabetes, intellectual disability and hearing impairment, but no brittle bones may at least partially be due to aberrant export and secretion of other proteins in a tissue specific manner.