SMARCA2 and intellectual disability-sparse hair-brachydactyly syndrome: According to Van Houdt et al. (2012) the facts that deletions encompassing the entire SMARCA2 gene do not cause NCBRS, that mice lacking functional Smarca2 do not present with major developmental abnormalities, and that the solely non-truncating mutations in NCBRS patients are located exclusively in the SNF2 ATPase domain suggest that these mutations most likely do not lead to haploinsufficiency, but rather have a specific dominant-negative or gain-of-function effect (Van Houdt et al., 2012 and references therein).