A nine-year-old boy suffering from a rare medical condition can only sport one fixed facial expression.

Justin Tiernan-Reese was born with Moebius syndrome – a neurological disorder that causes facial paralysis. He is unable to smile, frown, raise his eyebrows, or even close his eyelids, and asks his mother why he can't have a "smiley face".

However, his mother Jessica Tiernan-Reese from Shrewsbury says that despite all the challenges, Justin has adapted to his situation. He asks his mother to use phone filters while clicking his photos "so he can have a smile".

Jessica wants to raise awareness about this rare condition and help others who can't express their emotions facially.

"As Justin has gotten older he's started to notice that he is different. It's really difficult when he comes to me and says, "Mummy, why can't I have a smiley face? It's very difficult to explain to a child when they can't do something that everyone else can do. Kids can be nasty," she told the Daily Mail.

According to Moebius Syndrome Foundation's website, the cause of this condition is not known. It mostly results from a combination of environmental and genetic factors and affects two to 20 people per one million.

Jessica says she came to know about her son's condition after she had undergone some tests during her pregnancy, Daily Mail reported.

In the 20-week scan, the boy had displayed clubbed feet. Further test results confirmed that he had Moebius syndrome.

"The nerves were so weak that he didn't have the strength in his face to latch or feed. Doctors can't tell me what caused it. You can see signs of distress in a baby's changed face. But with him we couldn't, and still can't, tell if something was wrong. He could just manage to cry, but it wasn't much of a cry."

Some of the symptoms of the syndrome are respiratory problems, speech and swallowing disorders, eye sensitivity due to inability to squint, absence of lateral eye movement, drooling, dental problems, hearing impairment, hand/feet deformities and more, Moebius Syndrome Foundation states.

However going against all the odds, Justin has adapted to his condition and is able to eat and drink on his own.

"He understands that he is different. It's his own, personal battle. When it does come up, I explain this is why he is special," his mother said.

She says that several people keep staring at Justin and she hopes to encourage strangers to talk to him.

"I want people to understand. Justin' not going around with a sign saying, 'Don't talk to me because I can't smile'.

"People can talk to us. We want people to talk to us because that's how people learn about this syndrome. Just because it only affects a few people doesn't mean it doesn't matter."

According to Medscape website, the syndrome is congenital and nonprogressive and has no definitive treatment available.

"It was a gut-wrenching feeling not to experience my baby's first smile and to know he would never be able to have one," Jessica said.

But "He's adapted to life with the syndrome. He kind of owns it.

"We are grumpy in Great Britain. That's the way we are, you don't see many people smiling. We take it for granted that we can," Jessica added.