Inclusion Criteria:  Patients who  fulfill the diagnostic criteria for neurofibromatosis 1 are aged 16 years or over attend the national neurofibromatosis service at GSTT are capable of providing informed consent do not have any non neurofibromatosis 1 related co-morbidities that affect mobility or balance (confirmed with the treating clinician) are able to walk more than 10 metres without assistance of a person (may use walking aid/orthotics) Symptoms that have remained stable between the 2 testing sessions (14 days). This will be assessed with the use of a neurological examination (Power, Sensation, Co-ordination, proprioception and reflexes), the NFQOL questionnaire and a subjective question to the patient as to if they feel there have been any changes to their symptoms in the last 14 days (completed on a percentage, 0= no change, 100% large change impacting their function). The assessing clinician will determine if any change is a significant change based on a reduction in power of more than 1 point (Oxford scale 0-5) and if there is a significant change in scores in comparison with the published norms.  Exclusion Criteria:  Patients who  do not fulfill the diagnostic criteria for neurofibromatosis 1 are under the age of 16 years are unable to provide informed consent have non neurofibromatosis 1 related co-morbidities that affect mobility or balance (confirmed with the treating clinician) are unable to walk more than 10 metres without assistance of a person (may use walking aid/orthotics) Patients whose symptoms have not remained stable between the 2 testing sessions (14 days). This will be assessed with the use of a neurological examination (Power, Sensation, Co-ordination, proprioception and reflexes), the NFQOL questionnaire and a subjective question to the patient as to if they feel there have been any changes to their symptoms in the last 14 days (completed on a percentage, 0= no change, 100% large change impacting their function). The assessing clinician will determine if any change is a significant change based on The assessing clinician will determine if any change is a significant change based on a reduction in power of more than 1 point (Oxford scale 0-5) and if there is a significant change in scores in comparison with the published norms. If the participant has been involved in research which may impact the testing (e.g. changes in treatment which may impact their symptoms during the trial/currently involved in a study completing the same outcome measures and adding a level of learned bias) then they will not be invited to join the study.