1. The human genome Contains all the genetic material of an individual
Made up of DNA
Determines structure and function
Is inherited from our parents

2. Series of nucleotides (bases) A, G, C, T Organization:
genes
<2.0% of genome
genes
other regions

5. Variants/mutations
We inherit hundreds of variants/mutations from our parents
The DNA in our own cells acquires several new variants/mutations during a lifetime
Causes
environment – majority
cell division (DNA duplication)

6. 6 × 109 base pairs of DNA need to be replicated, packed and segregated every time a cell divides
Repeated up to a trillion (1012) times during the development of a human from a fertilized egg

7. Human genetic disorders
Monogenic disorders
Rare
> known (WHO)
Collectively occur in 1:200 individuals
Examples
Cystic fibrosis
Muscular dystrophy
Sickle cell anaemia
Osteogenesis imperfecta
Neurofibromatosis

8. Human genetic disorders
Polygenic/multifactorial disorders
Common
Important environmental component
Examples
Heart disease
Atherosclerosis
Cancer
Obesity
Diabetes
Hypertension
Autoimmune disease

9. Types of monogenic disorders
Recessive or dominant disorders
Autosomal or sex-linked disorders

10. Monogenic (single gene) disorders: autosomal recessive
Examples
cystic fibrosis
sickle-cell anemia
oculocutaneous albinism
phenylketonuria
Two mutated alleles i.e. one from each parent

12. Monogenic (single gene) disorders: autosomal dominant
Examples
myotonic dystrophy
familial hypercholesterolemia
neurofibromatosis
polycystic kidney disease
Huntington’s disease
One mutated allele i.e. from either parent

13. Monogenic (single gene) disorders: sex-linked
Recessive
Hemophilia, Duchenne muscular dystrophy
Usually affects men
Dominant
Very rare: hypophosphatemic rickets, Rett syndrome
Y-linked
Only in males
Neither dominant or negative since only one allele

14. Penetrance
The proportion of individuals carrying a particular mutation that express an associated phenotype
e.g. 95% penetrance: 95% of individuals with the mutation will develop the disease, while 5% will not
Causes of variation in penetrance
Age
Environmental modifiers
Genetic and epigenetic modifiers

15. Gaussian distribution
“Bell-shaped” curve
Individual molecule (e.g. enzyme)
Structure/function

16. Normal distribution and standard deviation
For the normal distribution, one standard deviation, this accounts for about 68% of the set, while two standard deviations from the mean account for about 95%, and three standard deviations account for about 99.8%

17. Body height and weight
Number of people
Height (cm)
Weight (kg)

18. Skin colour
Number of people
Pigmentation (skin colour)

19. Blood cholesterol levels
Number of people
Cholesterol

20. HIV/AIDS Adult-onset diabetes Cystic fibrosis Genetic component
Environmental
component