SMCHD1 and arhinia, choanal atresia, and microphthalmia: For patients carrying an SMCHD1 variant, we compared cells from a patient affected with BAMS carrying a mutation (BAMS-1; E136G) that causes an increased ATPase enzymatic activity, reported as a gain-of-function [6,8] to cells from a patient affected with FSHD2 carrying a mutation in the ATPase domain, never reported in BAMS and which abrogates SMCHD1 enzymatic activity (14586; FSHD2, Q194P) [9] (Figure 1B).