Which statement about Y-STRs is true?

Which statement about Y-STRs is true?

• A. They provide comprehensive individual discrimination on their own.
• B. They are inherited from both parents.
• C. They are useful for distinguishing male DNA in mixed samples but offer less discriminating power when used alone.
• D. They mutate too rapidly to be reliable for forensic use.

Answer: (C)

Y-STRs are male-specific markers on the Y chromosome that are passed from father to son. They’re especially useful in mixed DNA samples because they isolate the male contributor’s DNA from the female background, since females don’t carry the Y chromosome markers being analyzed. But because these markers are inherited as a paternal haplotype with little recombination, many male relatives share the same Y-STR profile. That means Y-STRs can indicate a male’s involvement and help separate male DNA in mixtures, yet they don’t provide as much individual discrimination on their own as autosomal STRs. They do mutate at some rate, but not so rapidly that they’re unreliable; the key point is their strength in mixtures and their limitation in distinguishing individuals without additional autosomal markers.

Y-STRs are male-specific markers on the Y chromosome that are passed from father to son. They’re especially useful in mixed DNA samples because they isolate the male contributor’s DNA from the female background, since females don’t carry the Y chromosome markers being analyzed. But because these markers are inherited as a paternal haplotype with little recombination, many male relatives share the same Y-STR profile. That means Y-STRs can indicate a male’s involvement and help separate male DNA in mixtures, yet they don’t provide as much individual discrimination on their own as autosomal STRs. They do mutate at some rate, but not so rapidly that they’re unreliable; the key point is their strength in mixtures and their limitation in distinguishing individuals without additional autosomal markers.