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Genetic Disease

Genetic Disease. By: Jean Liu ID: 08301016041. General Facts. Caused by an abnormality in an individual’s genome Can also be caused by environmental factors The abnormality can range from minuscule to major Point mutation (P) – insertion/deletion entirely inside one gene

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Genetic Disease

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  1. Genetic Disease By: Jean Liu ID: 08301016041

  2. General Facts • Caused by an abnormality in an individual’s genome • Can also be caused by environmental factors • The abnormality can range from minuscule to major • Point mutation (P) – insertion/deletion entirely inside one gene • Deletion (D) – removal of a gene or genes • C – whole chromosome extra, missing or both • Trinucleotide repeat disorder (T) – gene is extended in length

  3. Xeroderma PigmentosumWhat Is It ? • Very rare inherited skin disorder • A person is highly sensitive to the sunlight (photosensitive) • Autosomal recessive genetic disorder • DNA repair – ability of repair damage caused by ultraviolet (UV) light • Six times more common in Japanese people than in other groups • Around 1 in 40,000 • Equal numbers of male and female patients • Less than 40% of individuals with XP survive beyond age 20 years • Those with milder disease may survive beyond middle age * Malignancy – medical condition that can progress, potentially result in death; eg: tumors

  4. Xeroderma PigmentosumTypes

  5. Xeroderma PigmentosumHow is it inherited ? • Genetic Condition • Can be passed from generation to generation in • Autosomal recessive inheritance patter • Mutation must be present in both copies of the gene • Carrier – one copy of the gene mutation • When both parents are carrier, there is a 25% chance that the child will be affected

  6. Xeroderma PigmentosumSymptoms • Skin • Eyes • Neurological

  7. Xeroderma PigmentosumSkin Symptoms • Severe sunburn after a short sun exposure • May last for several weeks • Usually happens during a child’s first exposure to the sun • Development of freckles at an early age • Irregular dark spots • Thin skin • Excessive dryness of the skin • Premature aging of skin, lips, eyes, mouth and tongue • More than 1,000 times the risk of developing skin cancer

  8. Xeroderma PigmentosumEye Symptoms • Occur nearly 80% of the patients • Eyes are very sensitive to the sun (photophobia) • Irritated • Bloodshot • Cloudiness of the cornea • Darkening of the skin of the eyelids

  9. Xeroderma PigmentosumNeurological Symptoms • Only occur in 20-30% of people with XP • Tend to get worse over time • Hearing loss • Microcephaly • Spastic muscles • Stiffness or tightness of the muscles • Seizures • Intellectual impairment • Poor coordination

  10. Xeroderma PigmentosumClassifications • Mild • Light brown freckles on face • Moderate • Dark brown freckles on face • Burning on exposed parts of the body • Photophobia • Severe • Serious dark brown freckles • Burning on exposed/unexposed parts of the body • Cutaneous changes • Ocular changes

  11. Xeroderma PigmentosumCause

  12. Xeroderma PigmentosumComplications • Skin tumors • Most patients die of skin cancer early in adulthood • Eye tumors • Vitamin D deficiency • Some are hypersensitive to X-rays • Patients who smoke may develop lung cancer at a relatively young age

  13. Xeroderma PigmentosumDiagnosis • Tests • Blood samples • Urine samples • Skin biopsy • Eye exam • Clouding of the cornea – loss of transparency of the cornea • Keratitis – front part of the eye becomes inflamed • Lid tumors • Blepharitis – inflammation of the eyelash follicles • Fibroblast culture • DNA repair • UV sensitivity • Aminocentesis • Test before the birth of the child - take sample of fluid from the sac around the baby

  14. Xeroderma PigmentosumTreatment • There is no cure for XP so far • Many management methods to cope with the problems

  15. Xeroderma PigmentosumManagement • Physically • Reducing exposure to the sun • Sun glasses • Clothing (long sleeves, long pants, gloves) • Optical filtration • Lots and lots of sunscreens • Chemically • Reducing the number of keratoses with Isotretinoin • Housing • Halogen lamps * Keratoses – keratin (on the skin)

  16. Xeroderma PigmentosumManagement • Two parts • Headgear • Protect head and face • Suit • Covering the rest of the body • Filtering 100% UV-light

  17. Xeroderma PigmentosumPrevention • Focuses more on future problems • Frequent check-ups and examinations • Skin specialist (dermatologist) • Eye specialist (ophthalmologist)

  18. Xeroderma PigmentosumA Case In China • Wan Lao Yang – the girl who lives in the dark • An XP patient • Her facial tumors made it impossible for her to wear the UV protective suit • The cancer had spread to her lungs • Died on June 2006

  19. Genetic Disease By: Jean Liu ID: 08301016041

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