GROUP 4

XERODERMA PIGMENTOSUM

INTRODUCTION

XERODERMA PIGMENTOSUM, OR XP,

IS AN AUTOSOMAL RECESSIVE GENETIC DISORDER OF DNA

REPAIR IN WHICH THE ABILITY

TO REPAIR DAMAGE CAUSED BY ULTRAVIOLET (UV) LIGHT

IS DEFICIENT.

NORMAL CONDITIONwithout XP

DNA DAMAGES

Exposure to UV light Thymine dimer

No replicating DNA strand

REPAIR SYSTEMNucleotide excision repair

Recognization

Unwinding

Cleavage

Filling

Sealing

ABNORMAL

skin

NUCLEOTIDE EXCISION REPAIR

• Uvr-ABC excinuclease

• DNA Polymerase• DNA Ligase

GENE

SKINThe POL H gene

(encoded DNA polymerase eta (Pol η))

protecting cells from UV

thatinduced DNA damage

fix DNA damage

UV

Xeroderma pigmentosum

Type A, I, XPA Type E, V, XPE

Type F, VI, XPFType B, II, XPB

Type G, VII, XPGType C, III, XPC

Type V, XPVType D, IV, XPD

Type of XP & inherited mutation gene

autosomal recessive genetic disorder of DNA repair

Signs and Symptoms ofXeroderma 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 on minimum sun exposure

 Spidery blood vessels

Scaly and dry skin

Irregular dark spots on the skin

freckles

blister

Scaly skin

blister

Bloodshot

DIAGNOSIS Usually detected in early infancy 1-2 years Clue to diagnosis - severe sunburn after first

exposure to the sunlightThe 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

INCURABLE

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

CONCLUSION

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