Twin brothers with an extremely rare genetic disorder which experts said would limit their life expectancy have defied the odds to reach their teens.

Freddie and Louie Dawkins were born apparently perfectly healthy but were diagnosed with deadly Batten disease when they were 3 years old.

They are believed to be the only identical twins in the world with the CLN5 strain – a neurological condition which affects just one in every 300,000 births.

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Doctors told devastated parents Sarah Finney and Andrew Dawkins their sons would probably die before they were teenagers.

But thanks to a new drug trial, the twins celebrated their 13th birthdays last month with their first foreign trip to Spain.

The family has raised £160,000 (approx. $210,110) to fund a research project into the CLN5 Batten disease at Cardiff University.

The boys had been developing normally until their mother noticed their eyes beginning to flicker around age 3. 

The boys had been developing normally until their mother noticed their eyes beginning to flicker around age 3.  (SWNS)

Researchers have used the boys’ skin cells to try and turn off the cell which is prevalent in the CLN5 gene.

A drug company agreed to give them an experimental treatment which they have been taking since January.

“The drug trial has given us new hope of finding a cure," Dawkins, 40, who quit his job as a furniture maker to care for his sons, said. "It is what keeps us going. We want to give our sons as normal a life as possible. The fundraising has given us a focus. The funding has led to the trial drug that the boys have been taking this year. We can see they are not deteriorating as we were told they would."

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“The drug company want to see results of improvement in the boys if they are to keep funding it," he said. "The tablets costs £46 (approx. $60) each and the boys have three each a day. So we hope they can see the improvement. We are incredibly grateful for the public support. We’ve raised around £160,000 (approx. $210,110) so far but more funding is needed."

"Sarah and I are both full-time carers for the boys," he said. "Only seven other kids in the county have CLN5 and I believe Freddie and Louie are the only twins in the world to have it. CLN5 is one of the rarest forms of Batten. We will keep fundraising and do all we can to fight the disease."

The couple, who have been together for 16 years, was delighted when Finney fell pregnant in 2004.

Doctors had told Dawkins he was unlikely to be able to father children after undergoing grueling chemotherapy after being struck down with leukemia at age 19.

Finney was also warned the chances of her being able to conceive were low after suffering from endometriosis.

SWNS

While there is still no cure for Batten, the family has found hope in a clinical trial that has helped stop the progression of the disease in the boys. 

But against incredible odds, her pregnancy was healthy and Freddie was born weighing 3 pounds, 11ounces while Louie was born minutes later weighing 4 pounds, 20 ounces.

They sat up at the age of 11 months, took their first steps at 21 months, and even started to say their first words.

But before the age of 3, their mother noticed their eyes started to flicker and they tripped over things.

The boys were referred to a pediatrician at the City Hospital in Nottingham where tests discovered they were both blind, despite having been born with perfect eyesight.

In August 2010, they were diagnosed with Late Infantile Batten Disease (LIBD) and their parents were told the boys had less than 10 years to live.

The disease is an inherited disorder of the nervous system which emerges in early childhood.

The cruel disease leaves youngsters blind, bedridden, and mentally impaired - with the life expectancy for children with the disease between 8-12 years.

However, experts believe the latest research could offer new hope to sufferers of the disease.

“Our project focuses on identifying key differences of CLN5 patient cells compared to healthy cells to try to understand which change happens first in the cell," said PhD student Katie Shipley, who is working with Dr, Emyr Lloyd-Evans at Cardiff University on researching the disease. “If we know what these are, we can try and treat this to prevent other changes happening which lead to the cell not working properly.”