Thus, a variant of the human Kv1.3 gene is associated with low insulin sensitivity and impaired glucose tolerance (Tschritter et al., 2006), whereas Kv1.3−/− mice were protected from diet-induced insulin resistance (Xu et al., 2003) and obesity (Xu et al., 2004). Here, KCNA3 is linked to obesity due to melanocortin 4 receptor deficiency.