Psychiatric-Mental Health Nurse Practitioner Exam

Which genetic inheritance pattern is often present in more than one generation?

1. Autosomally dominant

2. X-linked recessive

3. Mitotic inheritance

4. Polygenic inheritance

The correct answer is: Autosomally dominant

The autosomal dominant inheritance pattern is characterized by a trait that is expressed when only one copy of the gene (from either parent) is present. This means that if an individual inherits the dominant allele, they are likely to exhibit the associated trait or condition, regardless of what allele they inherit from their other parent. As a result, this pattern can be observed across multiple generations within a family lineage. In families with autosomal dominant disorders, affected individuals have a 50% chance of passing on the trait to their offspring. Thus, it is common to see the condition manifest in successive generations, allowing for identification of the trait through family history. Examples of conditions with autosomal dominant inheritance patterns include Huntington's disease and certain forms of breast cancer. In contrast, X-linked recessive conditions typically show a pattern where males are more frequently affected, with the condition often skipping generations through carrier females who do not express the trait but can pass it on to their sons. Mitotic inheritance is not a recognized genetic inheritance pattern in the context of hereditary diseases, and polygenic inheritance involves multiple genes contributing to a single trait, which generally does not follow a specific predictable pattern across generations in the same way autosomal dominant traits do.