Al-Awadi Salwa J, Khaleefah Hayder A, Abdulfattah Shaimaa Y
College of Biotechnology, Al-Nahrain University, Baghdad, Iraq.
Biotechnology Research Center/ Al-Nahrain University, Baghdad, Iraq.
J Genet Eng Biotechnol. 2022 Aug 6;20(1):114. doi: 10.1186/s43141-022-00403-7.
The X-chromosome short tandem repeat (STR) polymorphisms are a particular tool in the fields of human population genetics and personal identification. It was necessary in investigating complex kinship or deficiency cases in conditions where information on mitochondrial DNA (mtDNA) or Y chromosome polymorphisms have been used to explore their direct paternal line. This study aimed to investigate the allele frequency of (12X-STR) of 200 unrelated males from different region of Baghdad City to serve as a reference data base for individual identification in Iraqi population.
Twelve X-STR loci (DXS7424, HPRTB, DXS8377, GATA31E08, DXS7423, DXS8378, DXS9895, DXS10074, DXS6809, DXS7133, DXS101, DXS6807) were successfully amplified by multiplex PCR and divided into four groups. According to measures of allele frequency, the higher alleles frequency were 16, 11, 46, 11, 14, 10, 15, 15.2, 35, 11, 25, and 11 while the lowest alleles frequency were 11, 9, 52,53, 7, 17, 14, 13, 12.2,17, 36, 15, 16, 22, 29, and 17 that observed at the 12 loci respectively. Forensic efficiency parameter for DXS8377 locus in the first group showed highest polymorphic allele in the Iraqi Arab population with the frequencies ranging from 0.005 to 0.16%. The power of discrimination (PD) value ranged from 0.663 for DXS7423 locus and 0.9066 for DXS8377 locus. In addition, the polymorphism information content (PIC) value ranged from 0.602974 for DXS7423 locus to 0.899206 for DXS8377 locus.
Overall the X-STR markers become used as an important source of information beside the autosomal and Y-STR markers, especially for kinship testing and haplotype analysis.
X染色体短串联重复序列（STR）多态性是人类群体遗传学和个人识别领域的一种特殊工具。在利用线粒体DNA（mtDNA）或Y染色体多态性信息来探索直系父系的情况下，研究复杂的亲属关系或缺失案例时，这种工具很有必要。本研究旨在调查来自巴格达市不同地区的200名无关男性的12个X-STR的等位基因频率，为伊拉克人群的个体识别提供参考数据库。
通过多重PCR成功扩增了12个X-STR基因座（DXS7424、HPRTB、DXS8377、GATA31E08、DXS7423、DXS8378、DXS9895、DXS10074、DXS6809、DXS7133、DXS101、DXS6807），并将其分为四组。根据等位基因频率测量，较高的等位基因频率分别为16、11、46、11、14、10、15、15.2、35、11、25和11，而在这12个基因座上观察到的最低等位基因频率分别为11、9、52、53、7、17、14、13、12.2、17、36、15、16、22、29和17。第一组中DXS8377基因座的法医效率参数显示，在伊拉克阿拉伯人群中其多态性等位基因最高，频率范围为0.005%至0.16%。鉴别力（PD）值范围从DXS7423基因座的0.663到DXS8377基因座的0.9066。此外，多态性信息含量（PIC）值范围从DXS7423基因座的0.602974到DXS8377基因座的0.899206。
总体而言，除常染色体和Y-STR标记外，X-STR标记已成为重要的信息来源，特别是在亲属关系检测和单倍型分析方面。
