Genetic problem what is it called is theyre some sore of treament for this?

I have some cousins who when they reach 18/ puberty they loose theyre ability to walk properly the parents were first cousins that got married initially they loose the ability to walk properly and start using the front lobe of theyre feet to walk around and later on with time they loose theyre ability to use theyre feet at all and theyre vocal ability to talk effectively goes as well. whats this genetic disorder called any ideas of any ways that they can be helped knw they use a stand but they almost can't position theyre feet correctly to walk and move where ever they need to which seem so much hard work plz any help would be highly liked.

I had cousins like that too. The three that I knew all ended up dying in their 20's. They were normal until teens and then started having trouble walking and later talking. It was sad to watch.
Thankfully, none had children.
Since it is genetic, nothing could be done.

It reminded me of Huntingdon's disease but came on a lot earlier.

I'm a nurse. It's hard to know without seeing it for myself or a complete medical history. I would write down all symptoms and seek the advice of a doctor. This is alarming and shouldn't be ignored.

This sort of question is best asked to a person with the correct medical qualifications not thrown open for guesswork on the internet. Your cousins could have any one of a number of conditions but you will end up getting inappropriate advice because it's not possible to diagnose someone from just a few lines of information. Get them to see a doctor and if necessary pay for a private consultation with a suitable consultant (possibly a neurologist but impossible to be sure from what you've said)