German twins who were the first ever babies treated for a genetic disease in womb thriving two years after doctors gave potentially lethal diagnosis

A pair of twins in Germany are thriving after becoming the first to get a drug treatment for a genetic disorder while still in the womb, the Daily Mail reports. 

Corrina's first son, Joshua, has very few teeth and insufficient sweat glands, meaning he could easily overheat and even die if his body temperature rises too high due to a genetic disorder called X-linked hypohidrotic ectodermal dysplasia.

When she became pregnant with twin boys, Corrina wondered if the same fate was inescapable for them. 

After finding out Joshua's diagnosis when he was two, Corrina got touch with Dr Holm Schneider, who researches the disorder.

Dr Schneider had had remarkable success treating developing animal fetuses for the disorder while they were in the womb, but had never tried to treat a human - let alone twins.  

Corrina decided to take the plunge. 

Her boys, Maarten and Linus became the first to get the in utero treatment and now, at the same age their brother was when he was diagnosed, the first-of-its kind procedure seems to have worked. 

For most parents, a sweaty car seat on a hot summer day would hardly be noteworthy, except perhaps something as something that would need to be cleaned.

But for Corrina and her husband, Tobias, 'when we discovered wet baby car seats in the first summer, we became really excited about the effect of the treatment,' she told CNN. 

Maarten and Linus look very similar to their older brother - all three boys have sparse hair so blonde it is nearly white and slight dark shadows under their blue eyes.

But the two-year-old twins have a protein that Joshua lacks, thanks to the experimental new treatment. 

People born with X-linked hypohidrotic ectodermal dysplasia (HED) inherit a faulty gene from the X-chromosome that leaves them with a dysfunctional protein contains instructions for the formation particular types of tissues during development in the womb.   

Sweat glands develop between the 20th and 30th weeks of pregnancy. Once fully formed, the sweat they secrete are crucial to the body's ability to regulate temperature. 

The protein is also involved in the formation of teeth.