One feels tempted to compare with this root PAK *náḳʷǝ 'cheek, face' (Ad., Kab. naḳʷ - Shagirov's /1, 278/ analysis of *ḳʷǝ here as *gʷǝ 'heart, middle' is not persuasive). However, there are at once two irregularities: one which is rather common (metathesis) and another - shift of *q̇ʷ to *ḳʷ - which is more difficult to account for. We can not offer any final solution.