Autosomal recessive

Definition

Autosomal recessive refers to a type of inheritance pattern where two copies of a mutated gene must be present for an individual to express a particular trait or disorder. This means that both parents must carry at least one copy of the recessive allele for their offspring to be affected. Conditions that follow this inheritance pattern often skip generations, as carriers can pass on the gene without showing symptoms themselves.

5 Must Know Facts For Your Next Test

1. Autosomal recessive disorders often manifest when an individual inherits two copies of a mutated gene, one from each parent.
2. Common examples of autosomal recessive conditions include cystic fibrosis, sickle cell anemia, and Tay-Sachs disease.
3. Parents who are carriers of an autosomal recessive gene have a 25% chance with each pregnancy of having an affected child if both are carriers.
4. Pedigree analysis can be used to track the inheritance patterns of autosomal recessive traits within families, helping to identify carriers.
5. Autosomal recessive traits can sometimes appear to skip generations, as carriers may not show any symptoms but can still pass the mutated gene to their children.

Review Questions

• How does the inheritance pattern of autosomal recessive traits differ from autosomal dominant traits in terms of parental genotypes and offspring outcomes?
  • In autosomal recessive inheritance, an individual must inherit two copies of the mutated allele (one from each parent) to express the trait. If both parents are carriers (heterozygous), there is a 25% chance their child will inherit both mutated alleles and show the condition. In contrast, with autosomal dominant traits, only one copy of the dominant allele is needed for expression, meaning even if one parent carries the dominant allele, there's a higher chance (50%) that the offspring will express the trait regardless of the other parent's genotype.
• What role does pedigree analysis play in understanding autosomal recessive disorders and their transmission in families?
  • Pedigree analysis is crucial for tracing the inheritance patterns of autosomal recessive disorders within families. By examining family trees, geneticists can identify carriers and affected individuals, revealing how the trait has been passed down through generations. This information helps in predicting the likelihood of future occurrences in descendants and can guide reproductive decisions for those aware of their carrier status.
• Evaluate the implications of being a carrier for autosomal recessive disorders on public health initiatives and genetic counseling.
  • Understanding carrier status for autosomal recessive disorders has significant implications for public health and genetic counseling. Knowledge about carrier screening can help inform individuals about their risks and potential impacts on future offspring. Genetic counselors can provide essential information and support to couples at risk, enabling them to make informed reproductive choices. Public health initiatives that promote awareness about these conditions can lead to earlier diagnosis and intervention, improving health outcomes for affected individuals.

Related terms

Genotype: The genetic makeup of an individual, consisting of alleles inherited from each parent, which determines specific traits or characteristics.

Phenotype: The observable characteristics or traits of an individual, resulting from the interaction of their genotype with the environment.

Carrier: An individual who has one copy of a recessive allele and does not show symptoms of the associated disorder but can pass the allele to their offspring.