Question

Select the incorrect statement with respect to pedigree charts.

• A. The person from whom the trait starts is known as the proband.
• B. A solid geometrical figure is used to indicate an unaffected individual.
• C. It is very useful during genetic counselling of married couples.
• D. It is an analysis of a trait that has run through several generations of a family.

Answer 1

The correct option is B A solid geometrical figure is used to indicate an unaffected individual.

Pedigree analysis is the study of the inheritance pattern of a particular trait from one generation to the next in a family.
In a pedigree chart, the individuals and their relationships are pictographically represented in the form of geometrical figures and lines. Here, a solid geometrical figure (square, circle or rhombus) refers to a figure which is coloured (either partially or fully). These figures refer to affected or carrier individuals respectively. Hollow or unfilled figures represent normal individuals.

In the family under study, the very first person who is suspected to be the carrier of the trait or is affected with the trait is known as proband. When genetic counselors take a family history to study how a condition or risk might be inherited, they often start with a proband.
A pedigree chart is very useful during genetic counselling. If the couple (either male partner or female partner or both) have a history of genetic diseases in their families, they can consult a genetic counsellor and get the probability of the inheritance of the disease to their offspring.