Our data, taken with previous studies demonstrating the role of the SWI/SNF complex in cardiovascular development, suggests a scenario in which small perturbations of the SMARCC1 subcellular distribution, brought on by defective transport of BBS6H84Y; A242S, lead to congenital heart defects in MKKS patients. Here, SMARCC1 is linked to McKusick-Kaufman syndrome.