Lecture 6 Flashcards
autosomal recessive inheritance
manifested when you have an alteration in both copies of the gene
if both parents carry an autosomal recessive disorder what is the chance of the child being affected
1 in 4
if a child is not affected what is the chance of them carrying the condition
2 in 3
pseudodominant inheritance
Since both parents carry the recessive allele, there is a 25% chance with each pregnancy that their child will inherit two copies of the recessive allele and therefore exhibit the trait.
The trait is then expressed in multiple generations of a family, resembling dominant inheritance even though the trait itself is recessive
autosomal recessive disorder in Western Europe
cystic fibrosis
autosomal recessive disorder in West Africa
sickle cell anaemia
autosomal recessive disorder in Middle and Far East
thalassaemia
sickle cell anemia
red cells becomes more fragile and break up
blockage of small blood vessels with fragmented red cell
Thalassemia
autosomal recessive disorders with chronic anemia
alpha thalassaemia
underproduction of alpha globin from the alpha globin gene cluster on chromosome 16
- common in south East Asia
Beta Thalassaemia
underproduction of beta globin from the beta globin gene on chromosome 11
- common in Mediterranean
Cystic Fibrosis
thick mucous secretions in lungs, digestive system and pancreas
what is the frequency of cystic fibrosis in Ireland
1 in 1600
damage done to lungs in Cystic Fibrosis
large volumes of infected sputum, chronic infection with damage to bronchi and fibrosis of lung
damage done to digestive system due to cystic fibrosis
blocked pancreatic ducts
failure to absorb food
in infants - blocked bowel due to thickened meconium
treatment for lung disease due to Cystic Fibrosis
antibiotics
physio
heart lung transplant
treatment for the digestive system due to Cystic Fibrosis
pancreatic enzyme supplements
high calorie diet
how is cystic fibrosis diagnosed
clinical symptoms and signs
excess levels of sodium and chloride in sweat
genetic testing
compound heterozygote with the example of cystic fibrosis
they have two different cystic fibrosis gene alterations
double heterozygote
a healthy person who carries two different autosomal recessive disorders
Oculocutaneous albinism
autosomal recessive disorder characterized by a lack of pigment in skin, iris and pigmentary layer of the eye
Locus Heterogeneity
more than one gene which causes the same clinical disorder
heterozygote advantage - sickle cell disease example
people who carry sickle cell disease may be more resistant to severe forms of malaria
heterozygote advantage - Cystic Fibrosis advantage
people who were carriers were more resistant to intestinal infections (cholera, dysentery)
