Transcript Important Genetic Disorders

Important Genetic Disorders
Bio
Definitions
• Autosomes- any chromosome that is not a
sex chromosome. Not the “X” or “Y”
• Sex-linked- genes located on the sex
chromosome. Usually on the “X”
• Nondisjunction- A chromosome mishap in
meiosis
A Karyotype is a photograph of the
chromosomes of a single cell.
Another view
Huntington’s Disease
• Symptoms: Gradual Brain tissue loss in
middle age.
• Defect: Inhibitor of brain cell metabolism
• Autosomal/somatic dominate
• 1/10,000
Cystic Fibrosis
• Symptoms: Mucus clogs lungs, liver,
pancreas
• Defect: Failure of chloride ion transport
mechanism
• Autosomal recessive
• 1/2080 whites most common disorder
Sickle Cell Anemia
• Symptoms: impaired blood circulation,
organ damage
• Defect: Abnormal hemoglobin molecules –
RBC’s
• Autosomal Recessive
• 1/500 African Americans -If heterozygous
will not get malaria
Tay-Sachs Disease
• Symtoms: deterioration of CNS in infancy.
• Defect: Defective form of enzyme
hexosaminidase A (Hex A)
• Autosomal recessive
• 1/1600 Jews of European desent
Phenylketonuria (PKU)
• Symptoms: Failure of brain to develop in
infancy; if untreated causes death.
• Defect: defective form of enzyme
phenylalanine hydroxylase
• Autosomal recessive
• 1/18,000 urine test, treated by diet until
puberty.
Hemophilia
• Symptoms: failure of blood to clot
• Defect: defective form of blood-clotting
agent.
• X-linked recessive
• 1/7,000
Muscular Dystrophy
• Symptoms: wasting away of muscles; short
life expectancy
• Defect: muscle fiber degenerate
• X-linked recessive
• 1/10,000 “Jerry’s Kids”
Down’s Syndrome
• Symtoms: Mental retardation with abnormal
physical features.
• Defect: extra “X” chromosome
• Non-disjunction of the 21st pair of
chromosomes
• Somatic chromosome
• Also called Trisomy 21
Klinefelter’s
• Symptoms: only in males, sterile, do not
develop 2nd sex characteristics. Below
normal intelligence
• Defect: extra “X” in 23 pair of
chromosomes
• Meiosis error- genotype XXY
Turner’s
• Symptoms: only in females, appear normal
at birth, become stockier & shorter than
other females- large necks, sex organs &
breasts do not develop- sterile
• Defect: missing “X” chromosome in 23rd
pair
• Non-disjunction of sex chromosome
• Genotype XO