A charity has warned that handing GPs control of health budgets would be a "disaster".
The Muscular Dystrophy Campaign says that many GPs remain ignorant about muscle-wasting conditions, and lack vital experience of treating them.
Almost half of the 650 patients questioned said they did not receive a correct or prompt diagnosis, and believed they had suffered at the hands of their GP.
The study also revealed that emergency hospital admissions for people with muscular dystrophy costs the NHS more than £81 million every year.
The Muscular Dystrophy Campaign says that around 15,000 people with the condition or a related muscular disease are taken into NHS hospitals every year - many of which could be avoided with better continuity of care, including in patients' homes.
The charity's acting chief executive, Robert Meadowcroft, said: "The experiences our patients have told us of when visiting their GPs have confirmed for us how disastrous a move to GP commissioning could be.
"Neuromuscular services have been neglected for years and this could make the situation even worse.
"It is unacceptable that a patient should be delivered such a devastating diagnosis and then not offered the best possible care and advice straight away, or in some cases not given a definite diagnosis at all."
Dr Laurence Buckman, Chairman of the British Medical Association's GPs Committee, said: "When GP consortia take responsibility for commissioning, specialised treatment such as this will remain in the hands of specialists and will not take place in the way the Muscular Dystrophy Campaign fears it will.
"It will be commissioned by GP consortia in the same way that it is now by primary care trusts.
"It should be remembered that the intention behind GP commissioning is that, by having people who are medically qualified making the commissioning decisions, patients will see an improvement to their journey through the NHS.
"Patients with muscular dystrophy deserve specialist advice and care, and GP consortia will want to ensure that they get it."
Copyright © Press Association 2010