Multifactorial Inheritance

Question 1

Mendellian inheritance

Answer 1

monogenetic
reccessive dominant
c/s follow mendelian if present in parent

Question 2

polygenic

Answer 2

most human disorders
incidence in relatives 2-4%
familial risk> general pop.
Many continuous/ quantitative phenotypes

Question 3

polygenic phenotype

Answer 3

determined by 2 or more genes at different loci
each one is additice
not D or R
difficult to predict
environmental factors affect

Question 4

Nature vs nurture

Answer 4

polygene accounts for height, however is food source limited height won’t be reached

Question 5

Diseases

Neural Tube defect

Answer 5

lack of folic acid during pregnancy
neural tube doesn’t close to form spinal cord
born w spina bfida
folic acid reduces rick by 70%

Question 6

Diseases

Acquired Childhood, Adult onset

Answer 6

Autism
Asthma
Diabetes mellitus
epilepsy
glaucoma
hypertension

Question 7

Congenital malformations

Answer 7

cleft lip/ palate
hip dislocation
heart defects
talipes- club foot

Question 8

If height was mendelian

Answer 8

1 gene, 2 alleles
Short, Average, Tall

evidence for environmental influence is regression to mean, tall parents have short children- doesn’t work for discontinuous ie cleft lip

Question 9

Liability model

Answer 9

among relatives familial incidence so curve shifts to right inc freq of malformation

Question 10

Familial frequency

Answer 10

Parent 50% in common
Aunt 25%
Cousin 12.5%

Question 11

Studying multifactorial

Answer 11

study sibling concordance

issues: onset age, rare linkage, heterogeneity