在今日的BMC Genetics上，来自加州大学的科学家们发表了一篇基因组研究文章，文章对比了非洲裔美国人和欧洲人的基因组信息，文章首次构建了非洲裔美国人的DNA序列拷贝数目变异copy number variant（CNV）图谱。
拷贝数目变异也称拷贝数目多态（copy-number polymorphism，CNP）是一种大小介于1kb至3Mb的DNA片段的变异，在人类基因组中广泛分布，其覆盖的核苷酸总数大大超过单核苷酸多态性fsingle nucle otidepolymorphisms，SNPs）的总数，极大地丰富了基因组遗传变异的多样性。CNV对于物种特异的基因组构成、物种的演化和系统发育以及基因组某些特定区域基因的表达和调控可能具有非常重要的生物学意义。
该文章作者加州大学Jorge Oksenberg的神经科学实验室博士后Joseph McElroy称，这一研究结果对非洲裔美国人多发性硬化症病的研究具有指导意义。Joseph还表示，以前对于CNV的研究都集中在白人身上，现在从整个基因组上分析非洲裔美国人的CNV对非洲裔美国人具有重要的意义。
研究小组选取385名健康非洲裔美国人和435名健康白人（欧洲血统或是北美血统）来进行研究，经过对比，研究者发现白人组有1972个CNVs，黑人有1362个CNVs具有显著的差异。白人17号染色体重复拷贝数尤其多，黑人15号染色体重复拷贝数也比较多。
研究者称，这些结果对某些疾病的研究具有重大的意义，比如说，类风湿性关节炎，糖尿病和Crohn氏疾病。（生物谷Bioon.com）
生物谷推荐原始出处：
BMC Genetics 2009, 10:15doi:10.1186/1471-2156-10-15
Copy number variation in African Americans
Joseph P McElroy , Mathew R Nelson , Stacy J Caillier and Jorge R Oksenberg
Background
Copy number variants (CNVs) have been identified in several studies to be associated with complex diseases. It is important, therefore, to understand the distribution of CNVs within and among populations. This study is the first report of a CNV map in African Americans.
Results
Employing a SNP platform with greater than 500,000 SNPs, a first-generation CNV map of the African American genome was generated using DNA from 385 healthy African American individuals, and compared to a sample of 435 healthy White individuals. A total of 1362 CNVs were identified within African Americans, which included two CNV regions that were significantly different in frequency between African Americans and Whites (17q21 and 15q11). In addition, a duplication was identified in 74% of DNAs derived from cell lines that was not present in any of the whole blood derived DNAs.
Conclusions
The Affymetrix 500K array provides reliable CNV mapping information. However, using cell lines as a source of DNA may introduce artifacts. The duplication identified in high frequency in Whites and low frequency in African Americans on chromosome 17q21 reflects haplotype specific frequency differences between ancestral groups. The generation of the CNV map will be a valuable tool for identifying disease associated CNVs in African Americans.
