Sánchez Silvia, Juárez Ulises, Domínguez Julieta, Molina Bertha, Barrientos Rehotbevely, Martínez-Hernández Angélica, Carnevale Alessandra, Grether-González Patricia, Mayen Dora Gilda, Villarroel Camilo, Lieberman Esther, Yokoyama Emiy, Del Castillo Victoria, Torres Leda, Frias Sara
Laboratorio de Citogenética, Instituto Nacional de Pediatría, Insurgentes Sur 3700-C Insurgentes Cuicuilco, P01090, Ciudad de Mexico, México.
Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad de México, México.
Mol Cytogenet. 2023 Jan 12;16(1):2. doi: 10.1186/s13039-022-00631-z.
The human genome presents variation at distinct levels, copy number variants (CNVs) are DNA segments of variable lengths that range from several base pairs to megabases and are present at a variable number of copies in human genomes. Common CNVs have no apparent influence on the phenotype; however, some rare CNVs have been associated with phenotypic traits, depending on their size and gene content. CNVs are detected by microarrays of different densities and are generally visualized, and their frequencies analysed using the HapMap as default reference population. Nevertheless, this default reference is inadequate when the samples analysed are from people from Mexico, since population with a Hispanic genetic background are minimally represented. In this work, we describe the variation in the frequencies of four common CNVs in Mexican-Mestizo individuals.
In a cohort of 147 unrelated Mexican-Mestizo individuals, we found that the common CNVs 2p11.2 (99.6%), 8p11.22 (54.5%), 14q32.33 (100%), and 15q11.2 (71.1%) appeared with unexpectedly high frequencies when contrasted with the HapMap reference (ChAS). Yet, while when comparing to an ethnically related reference population, these differences were significantly reduced or even disappeared.
The findings in this work contribute to (1) a better description of the CNVs characteristics of the Mexican Mestizo population and enhance the knowledge of genome variation in different ethnic groups. (2) emphasize the importance of contrasting CNVs identified in studied individuals against a reference group that-as best as possible-share the same ethnicity while keeping this relevant information in mind when conducting CNV studies at the population or clinical level.
人类基因组在不同水平上存在变异，拷贝数变异（CNV）是长度可变的DNA片段，范围从几个碱基对到兆碱基，在人类基因组中的拷贝数也各不相同。常见的CNV对表型没有明显影响；然而，一些罕见的CNV与表型特征有关，这取决于它们的大小和基因含量。CNV通过不同密度的微阵列进行检测，通常进行可视化处理，并使用HapMap作为默认参考群体分析其频率。然而，当所分析的样本来自墨西哥人时，这个默认参考是不充分的，因为具有西班牙裔遗传背景的人群在其中的代表性极低。在这项研究中，我们描述了墨西哥梅斯蒂索人四个常见CNV频率的变异情况。
在一个由147名无亲缘关系的墨西哥梅斯蒂索人组成的队列中，我们发现与HapMap参考（ChAS）相比，常见的CNV 2p11.2（99.6%）、8p11.22（54.5%）、14q32.33（100%）和15q11.2（71.1%）出现的频率出乎意料地高。然而，当与一个种族相关的参考群体进行比较时，这些差异显著减小甚至消失。
本研究结果有助于（1）更好地描述墨西哥梅斯蒂索人群的CNV特征，并增进对不同种族基因组变异的了解。（2）强调在研究个体中识别出的CNV与尽可能具有相同种族的参考群体进行对比的重要性，同时在进行群体或临床水平的CNV研究时牢记这一相关信息。
