Genetic Diseases - Cystic Fibrosis, PKU and Flashcards
Who was Archibald Edward Garrod?
An english physician who pioneered the field of inborn errors of metabolism - described alkaptonuria in 1902
What is congenital?
A condition apparent at birth - not necessarily due to genetics - may be a developmental error e.g. thalidomide
What is PKU?
A lack of phenylalanine hydroxylase which leads to a build up of phenylpyruvate which damages the brain and inhibits tyrosinase (the enzyme for making melanin)
What are the symptoms of PKU?
mental retardation, seizures, tremors, behavioral disorders
How common is PKU?
1/14000
How common are carriers of PKU?
1/60
What kind of inheritance is PKU?
recessive
What test is used to determine if infants have PKU?
The Guthrie heel prick test - test for phenylpyruvate
What is cystic fibrosis?
A mutation in a chloride channel protein active in membranes of the lungs, liver, pancreas, intestines, reproductive tract and skin
What are the symptoms of cystic fibrosis?
Impaired respiratory system, digestive system and reproductive system
What is the CF gene?
The gene for the cystic fibrosis transmembrane conductance regulator - a 27 exon gene
What is a common mutation in the CF gene?
deletion of phenylalanine in position 508
What test is used to test for CF in infants?
heel prick test - check for immunoreactive trypsin secreted by the pancreas - detects about 90% of cases
How many people have cystic fibrosis?
1/2500 births
How many people are carriers for cystic fibrosis?
1/25
What is the inheritance of cystic fibrosis?
recessive
What is the structure of collagen?
Timer of glycine, proline and alanine - where the hydrogen of the glycine fits into the centre
What is Ehlers Danlos Syndrome?
An autosomal dominant mutation that affects a gene that alters the structure, production or processing of collagen
What is Marfan Syndrome?
A mutation of elastic tissues - decreased production of fibrillin-1
What enzyme is affected in albinism?
Tyrosinase
What is the mutation in sickle cell anaemia?
Glutamate to a valine - the hydrophobic valine binds to a hydrophobic pocket present in deoxyhaemoglobin and forms an insoluble crystaline structure
What is porphyria?
A mutation in an enzyme involved in the synthesis of haem - 7 variations
