Eight charities, including Parkinson's UK, the Multiple Sclerosis Society and Epilepsy Action have jointly submitted evidence to the committee of MPs examining the Health Bill.
The charities argued that GPs would need support to commission services to deal with rare neurological conditions.
'GPs often have limited knowledge and experience of "low volume" services and the conditions they apply to,' the charities said. 'Therefore the NHS Commissioning Board should support GP consortia in this important area and the Bill should be amended to reflect this.'
Clare Moonan, health policy and campaigns manager at Parkinson's UK, said most GPs had very few patients with Parkinson's disease. GPs would need 'guidance from government and expertise from patients, professionals and third sector groups', she said.
The Alzheimer's Society argued that consortia would need input from local authorities and other health professionals. 'It is hoped that a multi professional approach to commissioning will result in improved community-based services to reduce early entry to costly residential care and avoidable hospital visits,' the charity said.
Diabetes UK has already expressed similar concerns. It said GPs need to set up links with secondary care to ensure services do not become fragmented.