Genetic Diseases - Cystic Fibrosis, PKU and

Question 1

Who was Archibald Edward Garrod?

Answer 1

An english physician who pioneered the field of inborn errors of metabolism - described alkaptonuria in 1902

Question 2

What is congenital?

Answer 2

A condition apparent at birth - not necessarily due to genetics - may be a developmental error e.g. thalidomide

Question 3

What is PKU?

Answer 3

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)

Question 4

What are the symptoms of PKU?

Answer 4

mental retardation, seizures, tremors, behavioral disorders

Question 5

How common is PKU?

Answer 5

1/14000

Question 6

How common are carriers of PKU?

Answer 6

1/60

Question 7

What kind of inheritance is PKU?

Answer 7

recessive

Question 8

What test is used to determine if infants have PKU?

Answer 8

The Guthrie heel prick test - test for phenylpyruvate

Question 9

What is cystic fibrosis?

Answer 9

A mutation in a chloride channel protein active in membranes of the lungs, liver, pancreas, intestines, reproductive tract and skin

Question 10

What are the symptoms of cystic fibrosis?

Answer 10

Impaired respiratory system, digestive system and reproductive system

Question 11

What is the CF gene?

Answer 11

The gene for the cystic fibrosis transmembrane conductance regulator - a 27 exon gene

Question 12

What is a common mutation in the CF gene?

Answer 12

deletion of phenylalanine in position 508

Question 13

What test is used to test for CF in infants?

Answer 13

heel prick test - check for immunoreactive trypsin secreted by the pancreas - detects about 90% of cases

Question 14

How many people have cystic fibrosis?

Answer 14

1/2500 births

Question 15

How many people are carriers for cystic fibrosis?

Answer 15

1/25

Question 16

What is the inheritance of cystic fibrosis?

Answer 16

recessive

Question 17

What is the structure of collagen?

Answer 17

Timer of glycine, proline and alanine - where the hydrogen of the glycine fits into the centre

Question 18

What is Ehlers Danlos Syndrome?

Answer 18

An autosomal dominant mutation that affects a gene that alters the structure, production or processing of collagen

Question 19

What is Marfan Syndrome?

Answer 19

A mutation of elastic tissues - decreased production of fibrillin-1

Question 20

What enzyme is affected in albinism?

Answer 20

Tyrosinase

Question 21

What is the mutation in sickle cell anaemia?

Answer 21

Glutamate to a valine - the hydrophobic valine binds to a hydrophobic pocket present in deoxyhaemoglobin and forms an insoluble crystaline structure

Question 22

What is porphyria?

Answer 22

A mutation in an enzyme involved in the synthesis of haem - 7 variations