Unmarried US twin sisters take wedding photographs with their ailing father

A pair of US single sisters have taken heart-warming wedding photographs with their dad who has Alzheimer’s disease.

Texas twins Sarah and Becca Duncan’s father, Scott, was diagnosed with Alzheimer’s disease in 2012, ABC News reported.

Mr Duncan, 80, has since been moved to a 24-hour nursing facility due to his failing health.

Spurred on by the reality of their father’s condition, the sisters decided to take part in an unconventional wedding photoshoot, despite both being unmarried.

"We want to capture the moment while we can,” Sarah told ABC News.

"Me and Sarah know that our dad is more than likely not going to be at our wedding… we’re just being realistic,” Becca added.

The 23-year old twins dressed up in flowing white wedding gowns and held colourful bouquets while they posed with their father.

The sisters said the professional photography session was “the best thing in the world”.

“Seeing him coming down the hall and seeing us in our wedding dresses and him smiling. It meant so much to us," Becca said.

"It's something that we're going to have for the rest of our lives.”