1. You already know…
- A chromosome is a structure that carries genetic information
Each cell normally has 23 pairs of chromosomes:
1 pair of sex chromosomes
22 pairs of autosomes
Both chromosomes in every pair of autosomes consist of the same genes in the same order (homologous chromosomes)
 Every person has 2 alleles for each gene

2. Autosomal Inheritance
Autosomal RECESSIVE Inheritance

3. Autosomal RECESSIVE Inheritance
A recessive genetic trait located on an autosome
Males and females are equally affected
Heterozygote
NO symptoms
Carrier
Homozygote recessive
- Shows symptoms of trait
Examples: Cystic fibrosis, albinism, sickle cell disease

4. Cystic Fibrosis
Most common fatal genetic disease affecting Caucasian children and young adults
Due to a mutation of a gene on chromosome 7 that encodes a regulator protein
Results in a production of abnormal mucus that causes blockages within the lungs and airways
Mucus also builds up in the digestive tract making it difficult to digest and absorb nutrients
No cure, however treatments are improving

5. Albinism Due to a mutation on chromosome 9, 11, or 15
People with albinism have little or no pigment in their eyes, skin, or hair
Unable to produce or distribute melanin
Vision and skin problems
Does not usually affect lifespan
Diagnosis: eye examinations

6. Sickle Cell Disease
Due to a mutation on chromosome 11 that encodes a subunit of the hemoglobin protein
Distorts red blood cells (RBCs) into a sickle shape
Sickle shaped RBCs get stuck in blood vessels and are unable to transport oxygen effectively
Damages organs and decreases immune function
No cure, reduces lifespan by 30 years
Most common among African- Americans

7. Autosomal DOMINANT Inheritance

8. Autosomal DOMINANT Inheritance
A dominant genetic traits located on an autosome
Males and females are equally affected
Homozygote dominant or heterozygote
- Shows symptoms of the trait
Homozygote recessive
- Normal
Example: Achondroplasia and Huntington’s disease

9. Achondroplasia Due to mutation of a gene on chromosome 4
More commonly due to sporadic mutation
Most common type of short-limbed
dwarfism
Health problems: shortness of breath,
obesity, problems with the spine,
buildup of brain fluid

10. Huntington’s disease Due to mutation of a gene on chromosome 4
Neurodegenerative disorder that leads to dementia
Functional abilities gradually worsen overtime
Medications help manage the symptoms, but treatments can not prevent the physical, mental and behavioural aspects
Time from the onset of the disease to
death is about years
Common causes of death: infections,
falls, inability to swallow food