A gene encoding a highly conserved transmembrane protein plays a key role in certain cases of severe intellectual disability, according to a study appearing this week in the American Journal of Human Genetics. The gene TMEM147 encodes a protein with functions at the nuclear envelope and the endoplasmic reticulum, but its involvement in human pathology remains uncertain. Through international data sharing, a team led by scientists from Inserm identified 23 children from 15 unrelated families who all had bi-allelic TMEM147 loss-of-function variants and who displayed similar intellectual disabilities, developmental delays, and facial dysmorphisms. An analysis of primary fibroblasts and granulocytes provided functional evidence of endoplasmic reticulum and the nuclear envelope dysfunction. While TMEM147 is ubiquitously expressed, co-expression data suggests a strong correlation with neurodevelopmental genes linking subcellular dysfunction to key genes involved in brain development. Overall, the findings indicate that TMEM147 "should be considered as a gene responsible for intellectual disability and should be considered as a potential differential diagnosis with chromatinopathies or RASopathies," the authors write.