Journal of Forensic Medicine ›› 2026, Vol. 42 ›› Issue (2): 121-129.DOI: 10.12116/j.issn.1004-5619.2024.540305

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Analysis of Abnormal Genotyping at Amelogenin Locus in Male Individuals

Zhenping LIU1(), Zhihua YE2, Jijun TONG1, Jiahui SONG3, Weiwei WU4, Honglei HAO4, Yanfang FU4, Xiandun ZHAI3()   

  1. 1.Forensic Identification Center of Jinhua Public Security Bureau, Jinhua 321000, Zhejiang Province, China
    2.Forensic Identification Center of Pujiang Public Security Bureau, Pujiang 322000, Zhejiang Province, China
    3.College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang 471023, Henan Province, China
    4.Institute of Forensic Science, Zhejiang Provincial Public Security Department, Zhejiang Key Laboratory of Forensic Science and Technology, Hangzhou 310009, China
  • Received:2024-03-24 Online:2026-07-08 Published:2026-04-25
  • Contact: Xiandun ZHAI

Abstract:

Objective To investigate the abnormal genotyping and its causes at the Amelogenin locus in male samples. Methods A total of 23 647 blood samples from unrelated male individuals were analyzed using the STRtyper-21G kit, and 38 samples with abnormal Amelogenin locus were identified. These samples were retested and classified using GlobalFilerTM and PowerPlex® 21 kits. Additional sex chromosome STR genotyping and Sanger sequencing were performed for samples with abnormal genotypes. Sequence-tagged site (STS) testing was conducted for samples suspected of Amel-Y microdeletions. Results Among above 38 samples, except for Amelogenin locus, all samples showed normal male sex chromosome STR typing. The detection rate of abnormal genotyping was 0.161% (38/23 647), which were categorized into three major types. Among them, 30 cases had Amel-X deletion: 5 cases had C→T mutation at position 372; 2 cases had G→A mutation at position 293; 23 cases had A→G mutation at position 304. There were 2 cases of Amel-Y deletion: 1 case of insertion mutation of TTAA at position 387, and 1 case of microdeletion of the short arm containing Amel-Y. Six cases of abnormal Amel-X/Y peak ratios were identified: using the STRtyper-21G kit, the abnormalities appeared as low Amel-X with absent Amel-Y, normal Amel-X with absent Amel-Y, normal Amel-X with low Amel-Y, respectively. However, retesting with GlobalFilerTM and PowerPlex® 21 kits consistently showed normal Amel-X with low Amel-Y. The GlobalFilerTM profiling showed that the peak heights of Amel-Y were comparable to those of the Y-InDel and DYS391 markers, and no abnormalities were detected by sequencing. Conclusion Amelogenin genotyping abnormalities occur at a measurable frequency in the population and are mainly associated with mutations, which can be categorized as Amel-X deletion, Amel-Y deletion, and Amel-X/Y peak ratio abnormality. Regarding normal Amel-X peaks with lower Amel-Y peaks, the possibility of mosaic loss of chromosome Y (mLOY) in samples, which is commonly observed in elderly males, should be considered and given attention.

Key words: forensic genetics, gene mutation, Amelogenin locus, Amel-X deletion, Amel-Y deletion, abnormal ratio of Amel-X/Y peak

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