Autosomal dominant

Definition

Autosomal dominant refers to a pattern of inheritance where only one copy of a mutated gene from an affected parent is sufficient to express the trait or disorder. This means that an individual with just one copy of the mutated gene has a 50% chance of passing it on to their offspring, which leads to a significant prevalence of the trait in successive generations.

5 Must Know Facts For Your Next Test

1. In autosomal dominant inheritance, males and females are equally likely to be affected, and the trait can appear in every generation.
2. Some autosomal dominant disorders, like Huntington's disease, show complete penetrance, meaning every individual with the mutated gene will develop the disorder, while others may exhibit variable expressivity.
3. An affected individual typically has one affected parent, but new mutations can also occur, leading to cases where there is no family history.
4. Examples of autosomal dominant disorders include Marfan syndrome, familial hypercholesterolemia, and neurofibromatosis type 1.
5. Genetic testing can help identify carriers of autosomal dominant conditions and provide important information for family planning and management.

Review Questions

• Compare and contrast autosomal dominant inheritance with autosomal recessive inheritance in terms of trait expression and inheritance patterns.
  • Autosomal dominant inheritance requires only one copy of a mutated gene for the trait or disorder to be expressed, resulting in a 50% chance of passing it on to offspring. In contrast, autosomal recessive inheritance necessitates two copies of the mutated gene for the trait to manifest, often skipping generations as carriers may not show symptoms. This results in different patterns of family history; while autosomal dominant traits are more likely to appear in every generation, recessive traits may be less visible until two carriers reproduce.
• Discuss the implications of variable expressivity in autosomal dominant disorders and how it affects patient management.
  • Variable expressivity in autosomal dominant disorders means that individuals with the same genotype can show different phenotypes or severity of symptoms. This complicates patient management since clinicians must account for this variability when assessing risk and treatment options. For example, two family members might carry the same mutation but experience vastly different health outcomes, making personalized care essential and emphasizing the need for genetic counseling.
• Evaluate how advancements in genetic testing have changed the approach to identifying and managing autosomal dominant disorders in families.
  • Advancements in genetic testing have revolutionized the identification and management of autosomal dominant disorders by providing precise information about genetic risks. Families can now utilize predictive testing to determine whether asymptomatic individuals carry mutations linked to specific disorders. This proactive approach allows for informed decision-making regarding lifestyle choices, surveillance for potential health issues, and family planning. Additionally, it opens up opportunities for targeted therapies and interventions that can significantly improve quality of life for affected individuals.

Related terms

Homozygous: A genetic condition where an individual has two identical alleles for a specific gene, one inherited from each parent.

Penetrance: The proportion of individuals with a specific genotype who exhibit the associated phenotype, influencing how likely it is for a genetic disorder to manifest.

Locus: The specific physical location of a gene or genetic marker on a chromosome.