CSS mutations in BRG1, the core ATPase, are either missense or in-frame deletions. They are located near the HSA domain and in the ATPase domain that contains an ATP-binding region and a helicase region (Figure 2). The absence of truncating mutations indicates that these mutations do not lead to complete loss of function similar to the null allele in Brg1 heterozygous knockout mice which display severe neural tube closure defects (Lessard et al., 2007). Rather, these CSS mutations may produce BRG1 that can be incorporated into BAF complexes which could then exhibit impaired or altered activity and act dominantly over the wild-type BRG1-containing complexes.
