KRAS c.35G > A is one of the most frequently reported substitutions in cancer (more than 14,000 records in COSMIC v82), and post-zygotic KRAS c.35G > A mutations have been reported to cause arteriovenous malformations of the brain (Nikolaev et al. 2018) and linear nevus sebaceous syndrome (Wang et al. 2015), but it has never been reported as a constitutional mutation. The gene discussed is KRAS; the disease is cancer.