GENETIC DISORDERS

1. GENETIC DISORDERS

2. A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. • Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes.

3. Gene Mutations • Can either be inherited from a parent or acquired • Failure of chromosome pairs to separate properly is called NON-DISJUNCTION • Non-disjunction will result in an imbalance of chromosomes • Having more or less genetic material is detrimental and is the resulting cause of Genetic Disorders

4. There are four major types of chromosomal mutations:

5. #1 DELETIONS: • involve deletion of a small portion of a chromosome

6. #2 DUPLICATIONS: • produces an extra exact copy of a specific region of a specific chromosome

7. #3 INVERSIONS: • re-order a segment of chromosome in backwards order • Not as detrimental as deletion or insertion

8. #4 – TRANSLOCATIONS: • Occurs when the information from one of two homologous chromosomes breaks and binds to the other • Usually this sort of mutation is lethal

9. In humans, non-disjunction is most often associated with the 21st chromosome, producing a disease known as Down's syndrome (also referred to as trisomy 21).

10. Sufferers of Down's syndrome display the following characteristics: • mild to severe mental retardation • short stocky body type • Upward slant to the eyes • large tongue leading to speech difficulties

11. Kleinfelter’s Syndrome • Males with Kleinfelter’s have an extra X chromosome (XXY) • Infertile – do not produce sperm • Enlarged breasts • Small penis and testicles • Sparse facial and body hair

14. Turner’s Syndrome • Missing or damaged X chromosome in females (Momosomy X) • Underdeveloped ovaries • Short stature, webbed neck • Sterile • Lacking secondary sexual characteristics

16. Cystic Fibrosis • Hereditary disease primarily affecting the lungs, pancreas and intestines • Caused by faulty channel proteins • Excess mucous clogs lungs causing a difficulty in breathing, prevents food from being digested • Diagnosed with a “sweat test” • Life expectancy of patients ~ 36 years

18. Duchenne’s Muscular Dystrophy • Generalized weakness and muscle wasting first affecting hips, pelvic area, thighs and shoulders • X linked recessive disorder • Eventually even muscles of the lung may weaken which may lead to respiratory failure

20. Albinism • Characterized by little or no pigment in the eyes, skin and hair • Major vision problems • Inherited altered genes do not make usual amounts of pigment melanin • Both parents must carry a defective OCA (oculocutaneous albinism) gene to have a child with albinism

22. Red-Green Colour Blindness • X-linked recessive disorder • Person cannot distinguish shades of red and green • Visual acuity is normal

23. Progeria • A rare disorder in where a person ages rapidly. • Caused by random, spontaneous mutation of one gene. • The mutated gene must be dominant over it’s recessive normal partner. • It is an autosomal disorder.

24. Progeria – Physical features.

25. Phenylketonuria or PKU People with PKU cannot consume any product that contains aspartame. PKU is a metabolic disorder that results when the PKU gene is inherited from both parents (autosomal recessive disorder) Caused by a deficiency of an enzyme which is necessary for proper metabolism of an amino acid called phenylalanine.

26. PKU • Phenylalanine is an essential amino acid and is found in nearly all foods which contain protein, dairy products, nuts, beans, tofu… etc. • A low protein diet must be followed. • Brain damage can result if the diet is not followed causing mental retardation…and mousy body odor (phenylacetic acid is in sweat).

27. PKU

28. Phenylalanine. Free diet