Pedigree Chart Sample Problems

Understanding pedigree charts is essential for anyone studying genetics or genealogy. These charts are used to track the inheritance of genetic traits through multiple generations of a family. By examining a pedigree chart, one can identify patterns of inheritance and predict the likelihood of certain traits being passed down to future generations. Below are some sample problems to help you practice interpreting pedigree charts.

In this pedigree chart, individuals affected by a dominant genetic disorder are represented by shaded symbols. Unaffected individuals are represented by clear symbols. Autosomal dominant inheritance means that a single copy of the mutated gene from either parent is enough to cause the disorder. Look for patterns of affected individuals appearing in every generation, as well as affected individuals having affected children.

Pedigree Chart Sample Problems

Problem 2: Autosomal Recessive Inheritance

In this pedigree chart, individuals affected by a recessive genetic disorder are represented by shaded symbols. Carriers of the recessive gene are represented by half-shaded symbols. Autosomal recessive inheritance requires two copies of the mutated gene, one from each parent, to cause the disorder. Look for unaffected parents who have affected children, as well as consanguineous marriages (marriages between blood relatives) that increase the likelihood of inheriting two copies of the mutated gene.

Problem 3: X-linked Inheritance

In this pedigree chart, individuals affected by an X-linked genetic disorder are represented by shaded symbols. X-linked inheritance means that the mutated gene is located on the X chromosome, leading to different inheritance patterns in males and females. Males have only one X chromosome, so they are more likely to be affected by X-linked disorders. Look for affected males with unaffected fathers, as well as carrier females who pass the mutated gene to their sons.