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Short tandem repeat (STR) multiplexes with the amelogenin (AMEL) gene as a gender marker have been used as a routine tool of forensic DNA analysis. It has been reported that AMEL-based gender detection could misidentify a known male as a female due to the dropout of amelogenin Y (AMELY) allele. Other gender markers, such as Y-chromosomal short tandem repeat (Y-STR), may be a substitution of AMEL and help the sex determination. In current study, employing AmpFlSTR® Sinofiler and AmpFlSTR® Y-filer™ PCR Amplification kit, 18 AMELY-negative males were identified. Accordingly, the incidence of the AMELY dropout was 0.227 ‰ (18/79,304) in Chinese population. Sequencing of AMELY allele and analyzing of azoospermia factors region suggested that 3 out of 18 misidentifications were induced by mutations in the primer-binding region of the AMELY, while other 15 sex misidentifications were results of Y chromosome microdeletions with variant lengths. Moreover, variant combination patterns of AMELY dropout and Y-STRs deletions were also observed. Our data suggested that Y-STR locus dropout may indicate more problems, especially in the mixed sample's interpretation. Results of haplogroup prediction showed that seven AMELY dropouts combined with variant Y-STR deletions can be classified as the J2 subdivision, suggesting that some of these Y chromosomes might descend from a common ancestor.

In this work, spherical polymer-based fluorescent sensor with high sensitivity for Hg 2＋ was first designed and synthesized. Dendritic hyperbranched poly(phenylene sulfide) (HPPS) with an average molecular weight of 10.910 kD and spherical conformation was synthesized via one-pot reaction procedure with 2,4-dichlorothiophenol as monomer. Because of aryl groups conjugated with sulfur atoms and dendritic topology, HPPS displayed remarkable chemical stability, fluorescent and multiple reaction sites. It inspires us to employ it as a smart matrix to develop polymer fluorescent sensor. Through the nucleophilic substitution and hydrolysis reaction, peripheral Cl atoms of HPPS were modified by NH 2 groups, and the resulted HPPS-NH 2 was achieved. The fluorescent sensor (HPPSNT) was fabricated by HPPS-NH 2 azo N＝N covalently bonded to small probe molecule Benzamide, It was found that the decreased absorption of fluorescent signal intensity was proportional to the mercury content concentration in a range of 2.5～100 nmol/L with a coefficient of correlation R of 0.9931, and a detection limit of 0.46 nmol/L. The mechanism of high sensitivity was discussed. HPPS was rich in sulfur atoms inside, which has a strong affinity for Hg 2＋ , Cu 2＋ , Fe 3＋, Ag ＋ , consequently, fluorescence of HPPS-NH 2 was quenched dramatically in the presence of these ions. As the peripheral small probe molecules preferentially reacted with Hg 2＋ via desulfurization and cyclization reaction, it is by such reactions instead of by quenching to cause fluorescence intensity of HPPSNT weakened. The decline of fluorescence intensity via desulfurization and cyclization reaction can be explained through the simulation calculation of bond length by Gaussian 09.

The male-specific Y-chromosomal short tandem repeat (STR) is a useful tool in forensic casework. The Y haplotype comprised of 16 loci, which is amplified simultaneously by AmpFlSTR(®) Yfiler(TM) PCR kit and provides strong exculpatory evidence in individual identification. We reported a rare Y-STR profile with a null allele at the DYS448 locus and an off-ladder allele at the DYS456 locus, when genotyping material from a vaginal swab in an alleged rape case. Sequence analysis revealed that the DYS448 null allele was a true type of null allele because of a total deletion of 11 upstream repeats and 9bp of the N(42) region, and there were numerous primer binding site mutations as well. The amplicon of the DYS456 locus was a small 92-bp fragment that was off-ladder, and sequencing analysis showed that there were only 10 repeats (AGAT)(10). This Y chromosome haplotype that was comprised of two variations provided helpful evidence for personal identification.

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