In a sample containing mixed male and female DNA, which type of marker is most useful to identify the male contributor while mitigating the female background?

In a sample containing mixed male and female DNA, which type of marker is most useful to identify the male contributor while mitigating the female background?

• A. Autosomal STR profile alone
• B. Mitochondrial DNA haplotype
• C. Y-STR profile
• D. SNP ancestry markers

Answer: (C)

When a sample contains DNA from both sexes, you want a marker that comes from a part of the genome that's present only in males to reveal the male contribution without being masked by the female DNA. Y-STR markers fit this perfectly because they are on the Y chromosome and are therefore present only in males. In a mixed sample, the Y-STR profile stands out as the male signal while the female DNA contributes little to or none of that same marker, making it easier to identify the male contributor. Autosomal STRs reflect DNA from both genders, so the female background can obscure the male profile you’re trying to see. Mitochondrial DNA haplotypes are inherited from the mother and are shared across all individuals regardless of sex, so they don’t help isolate the male contributor in a mixed sample. SNP ancestry markers give population-level background information rather than tying a specific male to a sample, so they’re not used to identify a particular male individual in a mixture. Thus, focusing on the Y-STR profile provides the best chance to identify the male contributor when female DNA is present in the mixture.

When a sample contains DNA from both sexes, you want a marker that comes from a part of the genome that's present only in males to reveal the male contribution without being masked by the female DNA. Y-STR markers fit this perfectly because they are on the Y chromosome and are therefore present only in males. In a mixed sample, the Y-STR profile stands out as the male signal while the female DNA contributes little to or none of that same marker, making it easier to identify the male contributor.

Autosomal STRs reflect DNA from both genders, so the female background can obscure the male profile you’re trying to see. Mitochondrial DNA haplotypes are inherited from the mother and are shared across all individuals regardless of sex, so they don’t help isolate the male contributor in a mixed sample. SNP ancestry markers give population-level background information rather than tying a specific male to a sample, so they’re not used to identify a particular male individual in a mixture.

Thus, focusing on the Y-STR profile provides the best chance to identify the male contributor when female DNA is present in the mixture.