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Which one of the following symbols and its representation, used in human pedigree analysis, is correct?
A
◆ (filled diamond) = male affected
B
□═○ (square and circle joined by a double line) = mating between relatives
C
○ (open circle) = unaffected male
D
□ (open square) = unaffected female
Detailed Solution
Standard pedigree symbols: a square represents a male and a circle represents a female; an open (unshaded) symbol is an unaffected individual and a filled (shaded) symbol is an affected individual.
A diamond represents an individual whose sex is unspecified, so a filled diamond is not 'male affected'.
An open circle is an unaffected female, not an unaffected male.
An open square is an unaffected male, not an unaffected female.
A single horizontal line joining a square and a circle shows mating; a double line shows mating between relatives (consanguineous mating).
Hence the correct representation is the square and circle joined by a double line = mating between relatives.
A diamond represents an individual whose sex is unspecified, so a filled diamond is not 'male affected'.
An open circle is an unaffected female, not an unaffected male.
An open square is an unaffected male, not an unaffected female.
A single horizontal line joining a square and a circle shows mating; a double line shows mating between relatives (consanguineous mating).
Hence the correct representation is the square and circle joined by a double line = mating between relatives.