Consanguinity in human populations Flashcards
(29 cards)
What is consanguinity?
Consanguinity refers to the union between individuals who share a common ancestor.
What is the coefficient of relationship?
The coefficient of relationship quantifies the percentage of DNA sequence shared by a pair of relatives.
How much DNA do siblings share on average?
Siblings share 1/2 of their DNA sequences on average.
How much DNA do first cousins share?
First cousins share 1/8 of their DNA sequences.
What is the chance of a heterozygous carrier of cystic fibrosis meeting another carrier in the general population?
The chance is 1 in 25.
How does consanguinity affect the likelihood of recessive diseases?
Consanguinity increases the chance that both parents carry the same disease-causing mutation.
What percentage of cystic fibrosis patients are offspring of first-cousin matings?
1.4% of cystic fibrosis patients are offspring of first-cousin matings.
What is Marfan syndrome?
Marfan syndrome is an autosomal dominant condition that affects ocular, skeletal, and cardiovascular systems.
What are common ocular defects associated with Marfan syndrome?
Common ocular defects include myopia and ectopia lentis.
What cardiovascular complication is most associated with Marfan syndrome?
Dilatation of the ascending aorta is a major cardiovascular complication.
What gene is most commonly mutated in Marfan syndrome?
The FBN1 gene is most commonly mutated in Marfan syndrome.
What is the role of the FBN1 gene?
FBN1 encodes a connective tissue protein called fibrillin.
What is the significance of missense mutations in FBN1?
Missense mutations can produce a more severe disease phenotype due to a dominant negative effect.
What are the treatment options for Marfan syndrome?
Treatment options include regular ophthalmological examinations, avoidance of heavy exercise, and β-adrenergic blockers.
What potential new treatment has been researched for Marfan syndrome?
TGF-β antagonists, such as losartan, have been researched as potential treatments.
What is the inbreeding coefficient?
The inbreeding coefficient is the probability that an individual is homozygous at a locus due to consanguinity in parents.
What is the probability that first cousins share a disease allele?
The probability is 1/8.
Fill in the blank: The coefficient of relationship for one route is given by _______.
(1/2)n−1, where n is the number of individuals in the route.
True or False: Most cases of Marfan syndrome are caused by mutations in the FBN2 gene.
False.
What percentage of Marfan patients develop mitral valve prolapse?
Mitral valve prolapse is seen in 1% to 3% of the general population.
What is the mortality type observed among cousin marriages in the Amish population?
Prereproductive mortality.
What is the range of recessive mutations that each person carries?
One to five recessive mutations that would be lethal to offspring if matched with another copy of the mutation.
This refers to homozygosity where two identical alleles for a trait can lead to genetic disease.
What is the expected outcome of matings between relatives?
More often produce offspring with genetic diseases.
This is due to the increased likelihood of homozygosity for recessive mutations.
How do mortality rates among offspring of first-cousin marriages compare to the general population?
Substantially greater than those of the general population.
Empirical studies have consistently shown this trend.
