For each pedigree shown, Identify which pattern(s) of transmission is/are impossible. Specify why transmission is impossible.

Key Concepts

Pedigree Analysis

Pedigree analysis is a diagrammatic method used to trace the inheritance of traits through generations in a family. It helps identify patterns of inheritance, such as autosomal dominant, autosomal recessive, X-linked dominant, and X-linked recessive traits. Understanding how traits are passed down allows for the identification of impossible transmission patterns based on the observed inheritance in the pedigree.

Modes of Inheritance

Modes of inheritance refer to the ways in which genetic traits are transmitted from parents to offspring. Key modes include autosomal dominant, where only one copy of a mutated gene is needed for expression, and autosomal recessive, where two copies are required. Recognizing these patterns is essential for determining which traits can or cannot be inherited based on the pedigree structure.

Genetic Consanguinity

Genetic consanguinity refers to the genetic relationship between individuals who share a common ancestor. In pedigrees, consanguineous unions can increase the likelihood of recessive genetic disorders appearing, as both parents may carry the same recessive allele. Understanding consanguinity is crucial for assessing the probability of certain traits being passed on and identifying impossible inheritance patterns.