Human genetic variation Flashcards
What are the applications for human genetics?
Academic Human history Individual advice Social policy Resources
What are the limitations of human genetics?
No experimental manipulation
No controlled matings
Long generation time
Requires specialist approaches
What is meant by ‘individual advice’ regarding human genetics?
Identification Parentage Genetic counselling Antenatal diagnosis Disease liability Cancer prognosis Therapy
What is meant by ‘social policy’ regarding human genetics?
Health care Abortion Genetic manipulation Legal medicine Genetic privacy
What types of resources are there for human genetics?
Human mutants
Clinical samples, e.g. tumours
Pedigrees
Historical perspective
What was the first human genetic polymorphism discovered?
The ABO blood group
Who discovered the ABO blood group system?
Karl Landsteiner
In the ABO blood group system, what are the dominant and recessive alleles?
A and B are co-dominant
O is recessive
In the ABO blood group system, which region has the highest average frequency of the A allele?
Europe
In the ABO blood group system, which region has the lowest average frequency of the A allele?
South America
In the ABO blood group system, which region has the highest average frequency of the B allele?
India
In the ABO blood group system, which region has the lowest average frequency of the B allele?
South America
In the ABO blood group system, which region has the highest average frequency of the O allele?
South America
In the ABO blood group system, which region has the lowest average frequency of the O allele?
East Asia
What are ABO antigens?
Carbohydrates on red blood cell glycoproteins, known as glycosphingolipids
What ABO antigen does the A allele produce?
N acetylgalactosamine
What ABO antigen does the B allele produce?
Galactose
What ABO antigen does the O allele produce?
No addition, i.e. it is a ‘null’ allele
What does the ABO locus encode?
Glycosyltransferase
What do both the Secretor and Lewis loci in the ABO blood group system encode?
Fucosyltransferases
What is the Rh blood group an important example of?
‘Preventative genetics’
What are the limitations of human genetics?
No experimental manipulation
No controlled matings
Long generation time
Requires specialised approaches
Give examples of types of human genetic variation
Blood groups
Protein polymorphisms
DNA polymorphisms
What defines a polymorphic locus?
When the frequency of most common allele is 0.02
For a 2-allele locus, what is the maximum value for H at p=q=0.5?
H = 2pq = 0.5
Define electrophoretic protein polymorphisms
Charge variation in erythrocyte and serum proteins
How can electrophoretic protein polymorphisms be detected?
Using simple, cheap tests
Who discovered electrophoretic protein polymorphisms in the 1960s?
Harry Harris
How many blood proteins are there? And how many of these are monomorphic and polymorphic?
104 blood proteins:
71 monomorphic
33 polymorphic (2-3 co-dominant alleles)
