Many patients pay for wheelchairs
People with muscle disease are denied health and social care services because they live in Wales, it is claimed.
The Muscular Dystrophy Campaign said its survey showed no specialist care co-ordinator for the 3,000 people with muscle diseases in Wales.
It also said 40% must pay for their own wheelchairs, while such services are readily available in England.
The Welsh Assembly Government said Health Minister Edwina Hart would "carefully consider" its findings.
The charity is calling for an urgent review of services across Wales.
The survey specifically highlighted the lack of a care co-ordinator in Wales as a major cause for concern.
Elsewhere in the UK, care co-ordinators act as the first point of call for muscle disease patients, giving them advice and guidance to help find specialist support.
A third of Welsh patients also have no access to a specialist neuromuscular consultant and 40% of them have no access to a physiotherapist or feel that they do not receive enough physiotherapy.
The 22 local health boards in Wales were also asked to provide information about their services for people with neuromuscular conditions and found that the majority do not support specialist clinics for adults or children.
Muscular Dystrophy Campaign chief executive Philip Butcher said: "For some families in Wales access to specialist care can be a matter of life or death.
"Their plight is made worse by the considerable delays and variations in the provision of essential equipment and barriers to living independently.
'Complex and confusing'"It is clear that health and social care services are patchy, complex and confusing.
"The report shows that three out of four people in Wales are missing out on the vital help of a care co-ordinator, whose role is to support and guide them through the system.
"We are calling on the local NHS commissioners and local authorities to urgently establish additional posts in Wales.
"I do know that Edwina Hart is taking this matter seriously and she has shown a clear commitment to improving standards of care for families in Wales."
On top of a general lack of health services, the survey also found 75% of families faced financial hardship as a result of muscle disease, with many having to pay for their own wheelchair.
The results come three years after the Government's National Service Framework for Long-Term Conditions, which pledged to improve quality of life and independence for people living with chronic conditions.
An assembly government spokersperson said the health minister would consider the survery findings, but added: "However, the independent review of neuroscience services, which Mrs Hart commissioned, will outline proposals on how to improve services across Wales.
"This is along with the ongoing work relating to children and young people's specialist services and the work about to start on neuromuscular diseases.
"She expects that people should see improvements as a result."
Muscle diseases weaken and waste muscles and can be inherited or acquired and affect people of all ages, backgrounds and nationalities.
There are currently no cures available to people with these kinds of conditions.