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GENETIC DISORDERS. 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. Gene Mutations.
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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.
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
#1 DELETIONS: • involve deletion of a small portion of a chromosome
#2 DUPLICATIONS: • produces an extra exact copy of a specific region of a specific chromosome
#3 INVERSIONS: • re-order a segment of chromosome in backwards order • Not as detrimental as deletion or insertion
#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
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).
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
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
Turner’s Syndrome • Missing or damaged X chromosome in females (Momosomy X) • Underdeveloped ovaries • Short stature, webbed neck • Sterile • Lacking secondary sexual characteristics
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
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
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
Red-Green Colour Blindness • X-linked recessive disorder • Person cannot distinguish shades of red and green • Visual acuity is normal
Colour Blindness Links . . . • http://www.youtube.com/watch?v=fYzmo9BgXtc&feature=related • http://www.youtube.com/watch?v=oADLENgvo4I&feature=related