Autosomal recessive inheritance Flashcards
(18 cards)
What is the typical recurrence risk for offspring of two heterozygous carriers of an autosomal recessive disease?
25%
This reflects the average outcome from a Punnett square involving two heterozygous carriers.
In autosomal recessive inheritance, which generation typically shows the disease phenotype?
Usually seen in siblings but not in earlier generations.
How does consanguinity relate to autosomal recessive diseases?
Consanguinity is present more often in pedigrees involving autosomal recessive diseases.
What is the genetic characteristic of individuals affected by autosomal recessive diseases?
Affected individuals are usually homozygous for the disease allele.
What is a key feature of the Punnett square for two heterozygous carriers of an autosomal recessive gene?
One-fourth of the offspring will be affected homozygotes.
What is the term for mating between related individuals, which may increase the risk of autosomal recessive diseases?
Consanguinity.
What is the recurrence risk when a carrier of a recessive allele mates with a homozygous affected individual?
50%
This situation is sometimes referred to as quasidominant inheritance.
What distinguishes dominant from recessive diseases in terms of clinical effects on heterozygotes?
Heterozygotes are clinically affected in dominant disorders, while they are usually unaffected in recessive disorders.
What is the expected outcome when two affected individuals of a recessive disease mate?
All of their children must also be affected.
What is the difference between autosomal dominant and autosomal recessive inheritance in terms of disease transmission?
Dominant diseases show a vertical transmission pattern; recessive diseases may appear in multiple siblings but not in earlier generations.
True or False: Autosomal recessive diseases affect males and females in unequal proportions.
False.
What is the impact of mutations on the severity of dominant diseases in homozygotes compared to heterozygotes?
Affected homozygotes are usually more severely affected than heterozygotes.
Fill in the blank: The disorder _______ is an example of an autosomal dominant condition with severe effects in homozygotes.
achondroplasia.
What role do biochemical carrier detection tests play in identifying recessive disease carriers?
They detect reduced levels of enzyme activity in heterozygotes.
How can the inheritance pattern of some diseases vary based on the mutation type?
Some diseases may be inherited in either autosomal dominant or autosomal recessive fashion depending on the mutation.
What is an example of a condition that can be inherited in both dominant and recessive patterns?
Familial isolated growth hormone deficiency (IGHD).
True or False: The terms dominant and recessive strictly apply to genes rather than traits.
False.
What is the expected phenotype of heterozygotes for the sickle cell mutation?
Clinically normal but at increased risk for splenic infarctions at high altitude.
