Question

Which one of the following symbols and its representation, used in human pedigree analysis is correct?

• A. $\square =◯$ = mating between relatives
• B. $◯$ = unaffected male
• C. $\square$ = unaffected female
• D. $⧫$ = male affected

Answer 1

Answer: (A)

A record of inheritance of certain genetic traits for two or more generations presented in the form of a diagram or family tree is called pedigree. In a pedigree a square represents the male, a circle the female, solid (blackened) symbol shows the trait under study or affected individual; unaffected or normal individual by an open or clear symbol and a cross or shade (of any type) in the symbol signifies the carrier of a recessive allele. Words can also be used in place of symbols. Parents are shown by horizontal line while their offsprings are connected to it by a vertical line. The offsprings are then shown in the form of a horizontal line below the parents and numbered with arabic numerals.