title: A new strategy for sperm isolation and STR typing from multi-donor sperm mixtures.
abstract: Mixed semen stains from multiple contributors are challenging samples in sexual assault casework, and it is crucial to obtain the DNA profiles of different donors to allow the evidence to play an important role in investigations and judicial proceedings. Current standard procedures, including preferential lysis, are incapable of separating single-source sperm from multiple male donors. Mixed profiles are often obtained and may not directly exclude or identify suspects. In this case, computational methods for mixture interpretation are often used, which rely on different types of calculation models. Here, we explored a new strategy for sperm cell isolation and detection from mixtures. It is a direct way to obtain genotypes of different sperm donors compared to computation-based mixture interpretation. Laser capture microdissection (LCM) and low volume-PCR (LV-PCR) were used for single sperm isolation and detection. The platform was sensitive; profiling of a single sperm cell generated a minimum of 13-16 loci in 73.1% of Y short tandem repeat (Y-STR) assays. A new Y-STR and autosomal STR multiplex system (YA-STR) were optimized by the combination of the Y-STR locus and 10 autosomal STR (auto STR) loci. The Y-STR locus acted as a tag to discriminate profile groups from different donors. Subsequently, consensus auto STR profiles of various persons could be received. The accuracy and availability of this method were evaluated on a three-donor semen mixture and found to be effective for the resolution of a multi-donor sperm mixture.
authors.affiliation: People's Public Security University of China, Beijing 100038, PR China.
authors.forename: Jun-Ping
authors.initials: JP
authors.lastname: Han
authors.affiliation: People's Public Security University of China, Beijing 100038, PR China; Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.affiliation: People's Public Security University of China, Beijing 100038, PR China; Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Xu
authors.affiliation: Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China; Key Laboratory of Medical Epigenetics, Tianjin Research Center of Basic Medical Sciences, Tianjin 300070, PR China.
authors.forename: Yi-Liang
authors.initials: YL
authors.lastname: Wei
authors.affiliation: Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China.
authors.forename: Xing-Chun
authors.initials: XC
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China.
authors.forename: Lan
authors.initials: L
authors.lastname: Hu
authors.affiliation: Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Ye
authors.affiliation: Key Laboratory of Forensic Genetics, Institute of Forensic Science, Ministry of Public Security, Beijing 100038, PR China; Beijing Engineering Research Center of Crime Scene Evidence Examination, Institute of Forensic Science, Beijing 100038, PR China. Electronic address: licaixia@tsinghua.edu.cn.
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Li
mesh_terms: D041322:Chromosomes, Human, Y; D016172:DNA Fingerprinting / Q000379:methods*; D004586:Electrophoresis; D005838:Genotype; D006801:Humans; D061346:Laser Capture Microdissection; D008297:Male; D018895:Microsatellite Repeats; D016133:Polymerase Chain Reaction; D013094:Spermatozoa / Q000166:cytology*
keywords: Forensic DNA analysis; Mixed semen stain; YA-STR