ABMGG Inheritance Patterns and Population Genetics Flashcards

In autosomal dominant inheritance, what is the recurrence risk for each offspring of an affected parent?

Answer: 50%

An affected parent carries one pathogenic allele on one of the two autosomes; each child has a 50% chance of inheriting that allele.

Which inheritance pattern is characterized by transmission exclusively through the maternal line with variable expressivity among family members?

Answer: Mitochondrial inheritance

Mitochondrial DNA is maternally inherited; all children of an affected mother may be affected but paternal transmission never occurs.

A couple is each a carrier of the same autosomal recessive variant. What is the probability that their child will be an unaffected carrier?

Answer: 50%

In a carrier × carrier cross, the expected genotypic ratio is 1 homozygous normal : 2 carriers : 1 affected, so carriers make up 2/4 = 50% of offspring.

Genomic imprinting results in disease when:

Answer: Both copies of a gene are inherited from the same parent (uniparental disomy) or one copy's imprint is erased

Imprinted genes are expressed from only one parental allele; uniparental disomy or imprinting center defects silence both working copies, causing disease.

What term describes the phenomenon where carrier females of an X-linked recessive condition are clinically affected due to skewed X-inactivation?

Answer: Manifesting carrier

When the normal X chromosome is preferentially inactivated in most cells, the carrier female expresses the disease to varying degrees and is called a manifesting carrier.

Hardy-Weinberg equilibrium predicts allele frequencies in a population remain stable under which set of conditions?

Answer: Random mating, no mutation, no selection, no genetic drift, no gene flow

Hardy-Weinberg equilibrium holds only when five conditions are met: random mating, no mutation, no natural selection, infinite population size, and no migration.