NF1 and plexiform neurofibroma: Secondly, two specific intragenic mutations (a 3-bp in-frame deletion NF1 c.2970_2972 del p.Met992del, and missense mutations affecting p.Arg1809) have been associated with distinct, but partially concordant mild clinical phenotypes, with the first being characterised by the absence of cutaneous neurofibromas and other serious complications [51,54], and the second by the absence of cutaneous or plexiform neurofibromas with Noonan–like features [55,56].