In which situation are X chromosome STR markers specifically more informative than autosomal STR markers for establishing paternity?
- A Paternity testing of a female child, since the father transmits his single X chromosome intact to all daughters ✓
- B Paternity testing of a male child when the mother is available
- C Identification of the source of a bloodstain at a crime scene
- D Determining whether two bones belong to the same individual
Correct answer: A. Paternity testing of a female child, since the father transmits his single X chromosome intact to all daughters
Explanation
B father passes his only X chromosome to every daughter without recombination affecting its identity in a simple comparison, so a daughter's paternal X STR alleles must all come from her father, giving strong exclusion power. B son receives the father's Y, not his X, making X STRs useless for father son confirmation. Autosomal markers remain the primary tool for tissue matching and general kinship.
Reference: Butler, Forensic DNA Typing, 2nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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