Genetics Flashcards
What is PKU?
Lack of phenylalanine hydroxylase
- build up of phenylpyruvate that cannot be converted to tyrosine damages the brain and inhibits tyrosinase -the melanin making enzyme
What is cystic fibrosis?
Primarily affects the respiratory system, digestive system and reproductive system
- causes a build up of mucus in the lungs which may lead to repeated chest infections
What is CFTR?
Located on chromosome 7, the CF gene
- product is the Cystic Fibrosis Transmembrane Conductance Regulator, a chloride channel protein
- there is a deletion of phenylalanine 508 which affects the permeability and conductance of the membrane
What are the different types of haemoglobinopathies?
- alpha and beta thalassaemias
- structural variants
- hereditary persistence of foetal haemoglobin (HPFH)
What is the mechanism of alpha and beta thalassaemias?
Decreased synthesis of one or more globin chains
- change the transcriptional levels, not the structure of the protein, so decreased synthesis
When do each of alpha and beta thalassaemias present and why?
- alpha chain is produced in foetal development so often see alpha-thalassaemia manifest in foetal development
- beta chain is produced after birth so don’t usually see in foetal development
What is the typical mutation in alpha-thalassaemia?
Majority caused by large deletions
What is the typical mutation in beta-thalassaemia?
Majority caused by point mutations causing reduced or no beta-globin
What is the consequence of thalassaemia?
Haemolytic anaemia, splenomegaly, skeletal deformities
What is the treatment of beta-thalassaemia?
Regular blood transfusions every 2-3 weeks for the rest of their life
- however this is introducing more iron which cannot be excreted –> iron chelation therapy
- bone marrow transplant would be the cure
What is sickle cell disease?
Caused by a point mutation (CTT –> CAT, glutamic acid –> valine)
- get anaemia and weakness, failure to thrive etc
