A woman has asked a judge to give doctors permission to stop providing life-support treatment to her severely ill daughter.

The woman, who is in her 70s, says her daughter, in her 50s, has suffered from Huntington’s disease, an inherited condition that damages nerve cells in the brain, for more than 20 years and shows no awareness of her surroundings.

She says medical evidence shows her daughter is in the end stages of life, and relatives and doctors agree that life-support treatment should stop.

The mother has launched litigation in the court of protection, where issues relating to people who lack the mental capacity to make decisions about treatment are considered, on her daughter’s behalf.

Mr Justice Peter Jackson is scheduled to decide what moves are in the daughter’s best interests after analysing the case at a hearing in London on 22 June.

He has ruled that the daughter – who has grownup children and is being cared for at a hospital in the Midlands – cannot be identified.

The judge, who has examined a written application and overseen a preliminary hearing, has agreed that the mother can instruct lawyers representing her daughter.

Yogi Amin, a solicitor with the law firm Irwin Mitchell who is representing the woman along with a barrister, Victoria Butler-Cole, said allowing a relative to be a “litigation friend” in such circumstances was rare.

Amin said staff from the office of the Official Solicitor, which was set up to offer independent help to people who are at the centre of litigation but lack the mental capacity to make decisions, were normally appointed to be a “litigation friend” and instruct lawyers.

He said he had told Jackson that the mother had no “interest contrary” to her daughter’s and the judge had decided that allowing the mother be a litigation friend would save time and public money.

“The mother and other members of the family have provided dedicated care for the last 25 years,” he said. “They have been a constant presence in her life. The mother personally visits her at least four times a week and has done throughout her stay in hospital.”

He added: “Her family have no interest in this case other than to ensure that her care and treatment are provided in accordance with what she would have wanted and what is in her best interests.”