Xeroderma Pigmentosum (XP) is a rare genetic disorder caused by a defect in nucleotide excision repair that results in an inability to repair UV-induced DNA damage. This leads to skin cancers developing at a very young age after only minimal sun exposure. Signs include severe sunburn, freckling, and development of skin cancers. Diagnosis is based on clinical findings and measuring DNA repair factors. Treatment focuses on protecting the skin from UV exposure and promptly removing cancerous growths. Most patients die young from skin cancers, but increased awareness and protection can improve prognosis.

1. Under the guidance of
Dr. K.Eswar Kumar
M.Pharm, Ph.D.
Pharmacology Division
A.U. College of Pharmaceutical Sciences.
Presenting by
K. Manasa Thriveni
B.Pharm
614209505004
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2. Contents
 Introduction
 Causes
 Aetiology
 Signs and Symptoms
 Diagnosis
 Treatment
 Prognosis
 Prevention
 Conclusion
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3.  We owe our lives to light from the sun, which provides the
energy captured during photosynthesis.
 But the sun also emits a constant stream of Ultraviolet rays that
ages and mutates the cells of our skin.
 The hazardous effects of the sun are most dramatically
illustrated by the rare recessive genetic disorder , Xeroderma
Pigmentosum(XP) .
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4. Xeroderma Pigmentosum (XP) is a rare genetic disorder that
occurs worldwide in all races and ethnic groups.
First described by Hebra and Kaposi in 1874 the disorder is
characterised by marked photosensitivity and premature onset
of all major types of skin cancer [1].
Definition:
It is characterised by inability of a cell to repair damage
caused by UV leading to genetic instability and skin cancer.
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5. Incidence:
Usually found at very young age(1-2yrs).
XP affects approximately one in 1,00,000 individuals
worldwide.
One in 250,000 persons in the United States and Europe (2)
Six times more common in Japanese people than in any other
groups (3)
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6. NORMAL CONDITION
WITHOUT
XP
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7. DNA DAMAGES
Exposure to UV light
Thymine dimer
DNA damage
NER
No replication of
DNA strand
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8. REPAIR SYSTEM
Nucleotide excision repair
Recognization
Unwinding
Cleavage
Filling
Sealing
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9. Nucleotide Excision Repair(NER)
 This system is responsible for removing the damaged
segments of DNA and restoring the original sequence of DNA.
The NER mechanism is composed of two types:
Transcription coupled(TCR):Which rapidly repairs areas of
DNA that are "active" and being transcribed into RNA
Global genome(GGR): Which repairs damage in the rest of the
genome more slowly
Seven XP genes are central to NER which includes many other
accessory proteins.
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10. ABNORMAL
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11. SKIN
The POL H gene
(encoded DNA polymerase eta
(Pol η))
Protecting cells from UV rays
Repairing of
DNA damage
Xeroderma
pigmentosum
UV
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12. Causes of XP
Autosomal recessive genetic disorder
Nucleotide excision repair(NER) enzymes are mutated
Reduced or eliminated number of NER enzymes
Metastatic malignant melanoma
Squamos cell carcinoma
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14. Autosomal Recessive Genetic Disorder
 In recessive disorders, the condition does not appear
unless a person inherits the same defective gene for the
same trait from each parent.
 If an individual receives one normal gene and one gene
for the disease, the person will be a carrier for the disease.
The risk of transmitting the disease to the children of a
couple, both of whom are carriers for a recessive
disorder, is 25 percent. Fifty percent of their children risk
being carriers of the disease.
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15. Aetiology
 The products of seven of these genes (XP-A through G) are involved
in the repair of ultraviolet-induced photoproducts in DNA by the
process of nucleotide excision repair (NER)5.
 The XPC and XPE proteins are needed to recognise the photoproducts
in DNA.
 XPB and XPD are part of a protein complex TFIIH, which opens up
the structure of the DNA around the site of the photoproduct.
 XPA protein verifies that proteins are in the correct position and then
the nucleases XPG and XPF cut the DNA on either side of the damage,
so that the damaged section can be removed and replaced with intact
DNA.
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16. Complementation groups for XP:
XPA
XPB
XPC
XPD
XPE
XPF
XPG
XPV
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XPA,XPC,XPE
XPB,XPD
XPF,XPG

17.  Patients defective in the XPC or XPE genes do not, in general,
have the extreme sunburn reactions or neurological abnormalities.
 Defects in the eighth XP gene do not affect NER 7.
 The DNA polymerases that normally replicate DNA cannot deal
with damage in the DNA template and specialised polymerases
have to be employed to get past the damage (translesion
synthesis).
 For UV damage, the cell uses DNA polymerase η, encoded by the
gene POLH and this gene is mutated in XP-V patients 8.
 Like XP-C and XP-E patients, XP-V patients rarely have extreme
sunburn reactions or neurological problems.
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18. Signs and Symptoms of
Xeroderma Pigmentosum
 Severe sunburn.
 Development of many freckles at an early age.
 Rough-surfaced growths (solar keratoses), and skin cancers.
 Eyes that are painfully sensitive to the sun and may easily
become irritated, bloodshot and clouded.
 Blistering or freckling on minimum sun exposure.
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19. Cont…
 Spider Veins
 Limited growth of hair on chest and legs
 Scaly skin
 Dry skin
 Irregular dark spots on the skin
 Corneal ulcerations
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Bloodshot
blister
freckles
Scaly skin

21. Diagnosis
Before birth:
Amniocentesis
Chorionic villous sampling
After birth:
 Severe sunburn after first exposure to the sunlight
 Based on clinical findings and family history,
skin, eye, and nervous system
 By measuring the DNA repair factor from skin or blood sample
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22. Treatment of XP
Cryotherapy
Removal of heat from the body.
Fluorouracil
Pyrimidine analogue used to treat cancer
Reduced exposure to sun’s UV rays
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Protection from
UV
Eye and skin
exam
Prompt removal
of cancerous
tissue
Neurological
exam
Psychososial
care

24. prognosis
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.
Less than 40% of individuals with the disease survive beyond age 20.
Some with less severe cases manage to live well up to 40 years.
Prevention
 Genetic counseling for those with Family history.
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25. Conclusions
 Though there is no cure for XP, increased awareness and
early diagnosis, followed by protection from daylight and
careful patient management, can improve the quality of
life and life expectancy of affected individuals.
 A major challenge for the future is to increase
understanding of the aetiology of the neurological
problems associated with the disorder in some individuals.
This should enable the development of treatments to
alleviate the neurological degeneration.
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26. References
1) Halpern, J.; Hopping, B.; Brostoff, J. (2008)“Photosensitivity,
corneal scarring and developmental delay: Xeroderma Pigmentosum
in a tropical country”.. Cases journal. 1:254.doi:10.1186/1757-1626-
1-254.PMC 2577106. PMID 18937855
2)Robbins JH, Kraemer KH, Lutzner MA, Festoff BW, Coon HG:
Xeroderma pigmentosum: an inherited disease with sun-sensitivity,
multiple cutaneous neoplasms, and abnormal DNA repair. Annals
Internal Med 1974, 80:221-248.
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27.  3) Hirai Y, Kodama Y, Moriwaki S, Noda A, Cullings HM, Macphee
DG, Kodama K, Mabuchi K, Kraemer KH, Land CE, Nakamura N.
Heterozygous individuals bearing a founder mutation in the XPA
DNA repair gene comprise nearly 1% of the Japanese population.
2006 ;Mutat Res, 601:171-178.
 4)Lehmann AR, McGibbon D, Stefanini M (2011). Xeroderma
pigmentosum. 2011 ;Orphanet J Rare Dis. 6: 70. Nov 1;6:70. doi:
10.1186/1750-1172-6-70.
 5)Stefanini M, Kraemer KHK: Xeroderma pigmentosum. In
Neurocutaneous Diseases Edited by: Ruggieri M, Pascual-
Castroviejo I, Di Rocco C 2008, Chapter 51:771-792.
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28. 6) Mieran Sethi,1 Alan R. Lehmann,1,2 Hiva Fassihi1: XERODERMA
PIGMENTOSUM: A MULTIDISCIPLINARY APPROACH,
2013;EMJ Dermatol. 1:54-63.
7) Lehmann AR, Kirk-Bell S, Arlett CF, Paterson MC, Lohman PHM,
de Weerd- Kastelein EA, Bootsma D: Xeroderma pigmentosum cells
with normal levels of excision repair have a defect in DNA synthesis
after UV- irradiation. 1975; Proceedings of the National Academy of
Sciences of the United States of America, 72:219-223.
8) Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa
M, Araki M, Iwai S, Takio K, Hanaoka F: The XPV (xeroderma
pigmentosum variant) gene encodes human DNA polymerase eta.
1999 ;Nature, 399:700-704.
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29. 9) Dr. Fawzia M. A. BUTT, Dr. Jeremiah R.MOSHI, DR.Siva
OWIBINGIRE. Xeroderma pigmentosum: a
Review and case series, 2010; Elsevier Ltd, 38(7):534-7
10) https://en.wikipedia.org/wiki/Xeroderma pigmentosum
11) http://rarediseases.org/rare-diseases/xeroderma pigmentosum/
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