French twns Vincent (R) and Thomas Seris buy fruits while shopping in a commercial centre in Bordeaux, November 12, 2014. [Photo/Agencies]

Born with Xeroderma Pigmentosum (XP), 21-year-old Vincent Seris and his twin Thomas cannot be exposed to the sun and its ultraviolet (UV) light, which could provoke precocious cancers due to a autosomal recessive genetic disorder of DNA repair.

Colloquially referred to as "Children of the Night" (Les Enfants de la Lune), the Seris twins are among 70 to 80 people in France who suffer from the genetic defect.

Thomas and Vincent have been testing a new protective mask for the last year which is transparent and ventilated and developed by several hospitals in France.

The French association "Les Enfants de la Lune" reports that there are between five and ten thousand such cases in the world.