Family Genetics And Inbreeding

Question 1

What is the consequence of inbreeding?

Answer 1

• Increase in homozygosity- higher risk of descendants receiving two copies of an allele- disease
• Reduced genetic variation
• Inbreeding depression
• Inbred populations have higher rates of genetic disease

Question 2

Outline the inbreeding coefficient

Answer 2

Proportion of loci homozygous due to shares ancestry

F= ΣN(1/2)^n
N=number of loops
n=number of ancestors

Brother sister= 1/4
Cousin= 1/16

Question 3

Give animal examples of inbreeding

Answer 3

Dogs
• Border Collie- Congenital myopathy- muscle weakness and early death
• King Charles spaniel- Syringomelia- brain into spinal chord

Song sparrows in wild
• Higher levels of inbreeding = lowered immune response

My bottleneck examples- European Bison and Cheetah
• Low levels of genetic diversity- species vulnerable to changing selection pressures

Question 4

Give human examples of inbreeding

Answer 4

Finland
• Set of 33 damaging recessive alleles found nowhere else in the world
• vLINCL- neurodegenerative disorder can be traced back to single male in a pedigree
• Records available due to church marriage records

Cystic Fibrosis
• 70% cases are one identical mutation- delta F508. Came from population genetically distinct to any present European group
(Morral et al., 1994)

Colon cancer patients and severe autism
• Larger segments of homozygous DNA than unaffected people

Question 5

What is isonomy?

Answer 5

Measurement of inbreeding by observing how often marriage occurs between people of the same surname