Search

The transmembrane protein TMEM147 has a dual function: first at the nuclear envelope, where it anchors lamin B receptor (LBR) to the inner membrane, and second at the endoplasmic reticulum (ER), where it facilitates the translation of nascent polypeptides within the ribosome-bound TMCO1 translocon complex. Through international data sharing, we identified 23 individuals from 15 unrelated families with bi-allelic TMEM147 loss-of-function variants, including splice-site, nonsense, frameshift, and missense variants. These affected children displayed congruent clinical features including coarse facies, developmental delay, intellectual disability, and behavioral problems. In silico structural analyses predicted disruptive consequences of the identified amino acid substitutions on translocon complex assembly and/or function, and in vitro analyses documented accelerated protein degradation via the autophagy-lysosomal-mediated pathway. Furthermore, TMEM147-deficient cells showed CKAP4 (CLIMP-63) and RTN4 (NOGO) upregulation with a concomitant reorientation of the ER, which was also witnessed in primary fibroblast cell culture. LBR mislocalization and nuclear segmentation was observed in primary fibroblast cells. Abnormal nuclear segmentation and chromatin compaction were also observed in approximately 20% of neutrophils, indicating the presence of a pseudo-Pelger-Huet anomaly. Finally, co-expression analysis revealed significant correlation with neurodevelopmental genes in the brain, further supporting a role of TMEM147 in neurodevelopment. Our findings provide clinical, genetic, and functional evidence that bi-allelic loss-of-function variants in TMEM147 cause syndromic intellectual disability due to ER-translocon and nuclear organization dysfunction., European Union (EU); Horizon 2020; Research and Innovation Program; Solve-RD Project; We thank the families and affected individuals for taking part in the study. We thank the University of Burgundy Centre de Calcul (CCuB) for technical support and management of the informatics platform. We thank the ‘‘Centre de Ressources Biologiques Ferdi- nand Cabanne’’ (CHU Dijon) for sample biobanking. This work was supported by grants from Dijon University Hospital, the ISITE-BFC (PIA ANR), and the European Union through the FEDER programs, EJP-RD (NSEuroNET), AIRC (IG21614), and Ital- ian Ministry of Health (5x1000). Sequencing for individual 15 was funded by the Institute for Information and Communications Technology Promotion (IITP) grant from the Korean government (MSIT) (2018-0-00861, Intelligent SW Technology Development for Medical Data Analysis). This study makes use of DECIPHER (http://decipher.sanger.ac.uk), which is funded by the Wellcome (www.ddduk.org/access.html).55 This research was made possible through access to the data and findings generated by the 100KGP. The 100KGP is managed by Genomics England Limited (a wholly owned company of the Department of Health and Social Care). The 100KGP is funded by the National Institute for Health Research and NHS England. The Wellcome Trust, Cancer Research UK, and the Medical Research Council have also funded research infrastruc- ture. The 100KGP uses data provided by individuals and collected by the National Health Service as part of their care and support. Several authors of this publication are members of the European Reference Network for Developmental Anomalies and Intellectual Disability (ERN-ITHACA).