What is the difference between autosomal STRs and Y-STRs in terms of inheritance and discrimination?

What is the difference between autosomal STRs and Y-STRs in terms of inheritance and discrimination?

• A. Autosomal STRs are inherited from both parents and provide high discrimination; Y-STRs are passed along the paternal line and provide male-lineage information with less individual discrimination when used alone.
• B. Autosomal STRs are only inherited from the father; Y-STRs from the mother.
• C. Autosomal STRs are not variable; Y-STRs are highly variable but only in females.
• D. Autosomal STRs are used for lineage tracing; Y-STRs provide high discrimination across populations.

Answer: (A)

Autosomal STRs sit on non-sex chromosomes and are inherited from both parents, so each person typically has two different alleles at a locus. This biparental inheritance combined with high natural variability gives autosomal STR profiles very strong power to distinguish between unrelated individuals.

Y-STRs, on the other hand, are on the Y chromosome and pass from father to son with little recombination. This means they track the paternal lineage and are great for determining male-line relationships and resolving male components in mixed samples. However, because many men share similar Y-STR haplotypes within a population, Y-STRs offer far less discrimination when used alone for identifying individuals.

So, autosomal STRs provide high individual discrimination due to biparental inheritance and high variability, while Y-STRs provide information about male lineage with lower individual discrimination when used by themselves.