Key messages
Our examination revealed, for the first time, that MFNG exhibited high expression levels during EndMT of heart valve development in mice. Our findings provide compelling evidence that MFNG plays a role in promoting EndMT mediated by the Notch signalling pathway. Our results identified, for the first time, a deleterious MFNG p. T77M variant that inhibited the EndMT process by downregulating the activity of the Notch signalling pathway, thereby preventing the normal valve formation. MFNG may serve as an early diagnostic marker and an effective therapeutic target for the clinical treatment of congenital heart valve defects.