Based on an a-priori hypothesis about the involvement of the TRESK potassium channel (encoded by the KCNK18 gene) in MA, Lafreniére et al. 2010 sequenced the entire gene region (i.e. a candidate-gene approach) and identified five variants in a case–control sample, of which one rare variant was subsequently shown to segregate perfectly with MA in a large multigenerational family (eight affected and 8 unaffected members) [26]. Here, KCNK18 is linked to microtia.