From Wiley via Jisc Publications RouterHistory: received 2021-08-18, rev-recd 2021-09-22, accepted 2021-10-02, pub-electronic 2021-10-11Article version: VoRPublication status: PublishedFunder: Cancer Research UK; Id: http://dx.doi.org/10.13039/501100000289Funder: European Union's Horizon 2020; Grant(s): 779257Funder: Medical Research Council; Id: http://dx.doi.org/10.13039/501100007155Funder: NHS EnglandFunder: NIHR Oxford Biomedical Research Centre ProgrammeFunder: Society for the Relief of Disabled Children, Hong KongFunder: Wellcome Trust; Id: http://dx.doi.org/10.13039/100010269; Grant(s): 203141/Z/16/ZAbstract: Only two families have been reported with biallelic TMEM260 variants segregating with structural heart defects and renal anomalies syndrome (SHDRA). With a combination of genome, exome sequencing and RNA studies, we identified eight individuals from five families with biallelic TMEM260 variants. Variants included one multi‐exon deletion, four nonsense/frameshifts, two splicing changes and one missense change. Together with the published cases, analysis of clinical data revealed ventricular septal defects (12/12), mostly secondary to truncus arteriosus (10/12), elevated creatinine levels (6/12), horse‐shoe kidneys (1/12) and renal cysts (1/12) in patients. Three pregnancies were terminated on detection of severe congenital anomalies. Six patients died between the ages of 6 weeks and 5 years. Using a range of stringencies, carrier frequency for SHDRA was estimated at 0.0007–0.007 across ancestries. In conclusion, this study confirms the genetic basis of SHDRA, expands its known mutational spectrum and clarifies its clinical features. We demonstrate that SHDRA is a severe condition associated with substantial mortality in early childhood and characterised by congenital cardiac malformations with a variable renal phenotype