dna mutation and genetic disease Flashcards
What are inherited disease? What are inherited disease caused by?
Inherited diseases are diseases caused by faulty genetic material that is passed on to future generations. They are sometimes called genetic disorders. Many inherited diseases are caused by mutations in DNA, resulting in faulty alleles that are not properly expressed. Mutations can be spontaneous or caused by exposure to mutagens such as radiation and certain chemicals.
What are the 3 main types of inherited disease? Give examples.
Single-gene diseases, these are caused by mutations in single genes. Examples include Huntington’s disease, cystic fibrosis and sickle cell anaemia. Multifactorial disease, these are caused by mutations in several genes combined with environmental factors. Examples include heart disease, Alzheimer’s, diabetes and cancer. Chromosomal disease, tese are caused by an abnormal number or structure of chromosomes. Examples include Down’s syndrome and Klinefelter syndrome.
State the mutagenic event
Deletion -> Duplication-> Inversion -> Substitution -> Translocation
What are carriers?
Like normal alleles, faulty alleles can be dominant or recessive. This means that people can have a copy of a faulty allele that codes for an inherited disease, but not have the disease themselves. These people are called carriers.
Is it important to know if someone is a carrier? Explain.
Yes it is important because eventually carriers can potentially pass the disease on to their children.
How to treat inherited disease?
Curing an inherited disease involves replacing faulty genes with normal genes. This is called gene therapy, but it is a very complex and relatively new technique, and has yet to be widely successful.
What is haemophilia?
Haemophilia is an inherited disease that prevents the body from controlling bleeding properly. Haemophilia is a recessivesex-linked disease that mainly affects males. People with haemophilia (haemophiliacs) are partly or completely missing a clotting factor that is needed to make their blood clot properly.
What are the symptoms of haemophilia?
The symptoms of haemophilia are, bruising easily, prolonged bleeding, and spontaneous bleeding.
How can haemophilia be cured?
Bleeding from minor grazes and cuts can usually be stopped relatively easily using just a sticking plaster.However, deep cuts and haemorrhaging can be very serious, affecting the joints, muscles and soft tissue.
How to manage haemophilia?
Haemophilia is treated by injections of clotting factors, although no permanent replacement is possible. Up to three injections per week may be needed.In the past, clotting factors were taken from donated blood, but this was often contaminated with hepatitis C and HIV viruses, leading to infection of haemophiliacs.Most clotting factor is now produced by genetically-engineering bacteria.
Explain haemophilia in males.
Haemophilia is far more common among males than females because it is a recessive X-linked disease. Males only have one X chromosome, which is inherited from their mother. Any allele contained within the chromosome, whether it is dominant or recessive, will always be expressed.This is because there is only one version of the allele and its effects will therefore not be masked by another version.
Explain haemophilia in females.
The recessive haemophilia allele is masked by the dominant normal allele on the other X chromosome. The female is therefore not affected by the disease, but is a carrier.
What happens if a female inherits two haemophilia alleles?
She will develop haemophilia, which is extremely rare.
State examples of a female carrier of haemophilia and a female that develops haemophilia.
X^H X^h = female carrier
X^h X^h = female haemophiliac
