Download GROUP 4 XERODERMA PIGMENTOSUM INTRODUCTION Xeroderma pigmentosum

Exposure to UV light
Thymine dimer
No replicating DNA
strand
Nucleotide excision repair
Recognization
Unwinding
Cleavage
Filling
Sealing
NUCLEOTIDE EXCISION
REPAIR
skin
• Uvr-ABC excinuclease
• DNA Polymerase
• DNA Ligase
GENE
UV
SKIN
The POL H gene
(encoded DNA polymerase eta
(Pol η))
protecting cells
from UV
thatinduced DNA
damage
Xeroderma
pigmentosum
fix DNA damage
Type A, I, XPA
Type E, V, XPE
Type B, II, XPB
Type F, VI, XPF
Type C, III, XPC
Type G, VII, XPG
Type D, IV, XPD
Type V, XPV
Signs and
Symptoms of
Xeroderma
Pigmentosum
Severe sunburn when exposed to
small amounts of sunlight. These often
occur during a child's first exposure to
sunlight.
Development of many freckles at an
early age
 Skin Cancer
Eyes that are painfully sensitive to the
sun and may easily become irritated
and bloodshot
Blistering
exposure
on minimum sun
 Spidery blood vessels
Scaly and dry skin
Irregular dark spots on the
skin
Bloodshot
freckles
blister
blister
Scaly
skin
DIAGNOSIS
 Usually detected in early infancy 1-2 years
 Clue to diagnosis - severe sunburn after first
exposure to the sunlight
 The diagnosis of XP is made on the basis of
clinical findings and family history
 The diagnosis of XP is based on skin, eye, and
nervous system
 XP can be diagnosed by measuring the DNA
repair factor from skin or blood sample
Treatment For XP
Protection from
UV
Eye and skin
exam
Prompt removal
of cancerous
tissue
Neurological
exam
Psychososial
care
PrOGNOsi$
*Many patients die at an early age from skin
cancers.but,if a person is diagnosed early,
does not have severe neurological symptoms
and takes all the precautionary measures to
avoid exposure to UV light, they may survive
beyond middle age.
< 40% of individuals with the
disease survive beyond age 20.
Some with less severe cases
manage to live well into their 40s