A photo of a teenager sitting by herself at her birthday party has been shared by her family as they appeal to the public to send her birthday cards.

Hallee Sorenson, who has autism, was pictured on her 18th birthday sitting at a table in the bowling alley eating cake by herself after her friends failed to show.

Rebecca Guildford posted the appeal on Facebook and it has been shared more than 185,000 times.

Ms Guildford hopes to rectify her cousin's disappointment of last year by asking the public to "flood her mailbox with birthday cards from all over!"

She hopes to give her cousin a special birthday when it comes around in July.

She wrote: "My cousin is a beautiful young woman who will always have the mind of a child. So as you can imagine, she was heartbroken and beyond sad. She was hurt."

She said: "Hallee is funny, sweet, caring, smart, an athlete, a jigsaw puzzle champion, a wonderful student, and a best friend to all. She is also a person who just happens to have autism. She has never let that small detail define who she is as a person - which is why I refuse to use it as something to describe her."

As the request spread across social media, several people inquired about sending gifts.

"That is incredibly sweet of all of you and my family is very appreciative. That being said, gifts truly aren't necessary. A nice card would be just fine!!! Thank you so much."