Human Biology (Year 12)
What conditions do I need to know?
The two gene mutation conditions that you need to have an understanding of are:
Duchenne muscular dystrophy
Cystic fibrosis (CF)
What is Duchenne muscular dystrophy?
Duchenne muscular dystrophy is caused by a gene mutation and results in a wasting of the leg muscles, following by the arms, shoulders and chest.
The disease may occur through gene mutation, which may arise through a mutation in the mother which may then be inherited by her sons (as the gene affects the X chromosome). The mutation may also occur in a male zygote so that the child develops the disease.
DND usually becomes noticeable around 3-5 years of age, as muscle weakness becomes evident. Eventual death will result due to failure of the respiratory muscles, and boys are unlikely to live for more than 20-25 years with the condition.
What is Cystic fibrosis?
Cystic fibrosis is a genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections.
It is caused by a mutation which occurs in a huge gene on chromosome 7; the gene has the code for 1480 amino acids which makes up a protein that regulates the passage of chloride ions across the cell membrane.
Wheezing or pneumonia
The allele is recessive, and so must be inherited from both parents.
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