TRPM4 and Heart block: Interestingly, two missense variants affecting Leu91 (TRPM4 p.L91F and TRPM4 p.L91P) have already been reported in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/?term=TRPM4+Leu91), also associated with progressive familial heart block, highlighting the importance of leucine in position 91 for the proper structure and function of the channel.