health

The cause of xeroderma pigmentosum is a mutation in any of eight genes
(on eight different chromosomes) known to affect the production of the
enzymes responsible for the repair of DNA in sunlight-damaged skin
cells. There are eight subtypes of XP that vary somewhat in the severity
of symptoms depending on which of the eight genes has been affected
by a mutation. The most common subtype, known as XPA, is also the
type most likely to be associated with neurologic symptoms.
A child must inherit a defective gene from both parents in order to
develop XP. A person who has only one copy of the gene mutation is
called a carrier. When both parents are carriers of a recessive gene mutation,
there is a 25 percent chance that a child will inherit two mutations
and develop XP.

in addition to the symptoms that have already been described, children
with xeroderma pigmentosum may also have:

• Raw patches of broken skin oozing tissue fluid
  
• Premature aging of the lips, eyes, mouth, and tongue
  
• Cancer developing on the tip of the tongue
  
• Limited growth of body hair on the chest and legs
  
• Increased vulnerability to infectious diseases