The WBSCR22:TRMT112 complex, homolog of the Bud23:Trm112 complex in yeast (Ounap et al. 2013), methylates guanosine-1639 of 18S rRNA at the N(7) position of the guanine base (Haag et al. 2015, Zorbas et al. 2015). The WBSCR22:TRMT112 complex but not its methylase activity is required for efficient processing of precursor rRNA at site 2 and site 3 (Haag et al. 2015, Zorbas et al. 2015). Hemizygosity at the region containing WBSCR22 causes Williams-Beuren syndrome (Doll and Grzeschik 2001).