Genetics and Human Disease Flashcards Preview

Pharmacogenetics Midterm > Genetics and Human Disease > Flashcards

Flashcards in Genetics and Human Disease Deck (22):
1

Pleiotropism

a mutation in a single gene can lead to many effects

2

genetic heterogeneity

a mutation in multiple genetic loci may produce the same trait

3

Autosomal dominant disease

late age of onset
only need one parent to carry defective gene

4

autosomal recessive

earlier age of onset
BOTH parents must carry defective gene

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Examples of autosomal dominant diseases

1. Huntington's disease
2. Familial hypercholesterolemia
3. Marfan syndrome

6

Huntington's disease

triplet repeat on chromosome 4 --> excessive # of glutamine residues --> dysfunctional protein builds up --> toxic to GABA neurons

7

Familial hypercholesterolemia

defective LDL receptor --> very high LDL levels in the blood

8

Marfan syndrome

mutation in fibrillan protein --> weak extracellular matrix

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Examples of autosomal recessive diseases

1. Phenylketouria (PKU)
2. Cystic fibrosis
3. Sickle Cell Anemia

10

Phenylketouria (PKU)

defective phenylalanine hydroxylase --> phenylalanine is not catabolized --> buildup in CNS causes mental retardation in infants

11

Cystic fibrosis

defective chloride ion channel --> thickened mucus secretions
protects against typhoid

12

Sickle Cell Anemia

defective hemoglobin which precipitates at low O2 tension --> sickling of RBC's --> buildup and hypoxia

13

X-linked recessive diseases

males most affected
1. hemophilia
2. G6PD deficiency
3. Diabetes insipidus
4. Fragile X Syndrome

14

Hemophilia A & B

defect in clotting factors VIII and IX --> prolonged bleeding due to inability to form fibrin clot

15

Diabetes insipidus

mutation in AVPR2 receptor --> defective vasopressin receptor

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G6PD deficiency

most common enzyme defect in humans
usually asymptomatic until hemolysis is triggered --> RBC's unable to repair

17

Fragile X Syndrome

triplet repeat in FMR1 gene
affects brain development

18

Non-dysjunction

chromosomes do not separate normally

19

Examples of diseases from non-dysjunction

1. Down's syndrome (trisomy 21)
2. Turner's syndrome (X0)= only one X chromosome
3. Klinefelter's syndrome (XXY)= extra X

20

positive selection

confers a survival advantage
ex: alcohol tolerance, lactose tolerance
ex. Sickle Cell carriers are protected from malaria, Tay Sach's protected against TB, Type AB blood resistant against cholera

21

multiple sclerosis

incidence is higher in countries far from the equator (US, Canada, Northern Europe)

22

Venous thrombosis

increased risk in pts who are oral contraceptive users with the Factor V Leiden mutation (majority are AA substitution at position 506) --> makes them more predisposed to having blood clots
most frequent CV event in young women