Desperate Search For Missing Sydney Teenager With Autism

Police are desperately searching for a missing Sydney teenager who was last seen in the early hours of Friday morning.

Catherine Nguyen, 19, was last seen in her family home at Chester Hill in the city's west at around 2:30am on Friday.

When her sister woke up just four hours later, she found the front door open and the 19-year-old missing, police said in a statement.

Catherine, who has autism, is known to frequent the Sydney CBD and is described as being of Asian appearance with short black hair and olive skin.

Police said she was last seen wearing a green and brown T-shirt with navy blue long pants and was carrying a green shopping bag.

The alarm was raised on Friday afternoon but by night time police confirmed to 10 daily there was still no sign of the missing teenager.

Anyone who may have seen Catherine or know of her whereabouts is being urged to contact Crime Stoppers on 1800 333 000.