Neurofibromatosis type 1 (NF1) is a common genetic disorder affecting 1 in 2500 individuals. Many individuals are mildly affected but a third of affected individuals unfortunately may develop one or more of the serious complications in their lifetime. One such complication is a benign tumour of the nerve to the eye (optic pathway glioma (OPG)) seen in 15% of  children on scans but only 5-6% get symptoms. There is no way to predict who will develop an OPG and how they will be affected. This study has identified that individuals with OPGs are more likely to have changes in a specific region of the NF1 gene and this is something which may allow a simpler method of detection. Further studies are now needed to confirm this finding and also to see whether we can further predict the nature of the OPG by the specific gene change. (Dr. Saba Sharif, http://jmg.bmj.com/content/early/2011/01/28/jmg.2010.081760?papetoc=)