Recessive Disease 2

Question 1

Sickle cell disease

Answer 1

Abnormally shaped (sickled) red blood cells
Chronic anemia
Impairment of growth and development
Increased susceptibility to infections
Blocking of blood vessels in extremeties

Question 2

Mutation that causes sickle cell disease

Answer 2

Mutation in beta-globin gene

2 beta-globin chains and 2 alpha-globin chains in hemoglobin

Question 3

Alpha thalassemia

Answer 3

Reduced alpha-globin
People have 4 alpha genes: most severe viable form of disease involves mutations in 3 of 4 alpha genes
Most severe: beta chains precipitate, hepatosplenomegaly (marrow fills up, so blood cells are made in liver and spleen)

Question 4

Mutation that causes alpha thalassemia

Answer 4

Mutation of alpha globin gene(s)

Question 5

Beta thalassemia: 2 severities and causes

Answer 5

Minor severity: one mutant beta chain gene
Major severity (Cooley’s anemia): absence of beta chain synthesis (2 mutant beta genes)
Mutation of beta globin chain

Question 6

Recessive dystrophic epidermolysis bullosa: symptoms and mutation

Answer 6

Extremely fragile skin: easily blistered

Caused by mutations in type VII collagen (holds epidermis and dermis together)