2015年4月7日訊 /生物谷BIOON/ --目前,全外顯子測序和全基因組測序技術在遺傳分析和發現導致疾病發生的潛在基因突變方面應用越來越廣泛,隨著測序技術的不斷迭代更新,越來越成熟,昂貴的價格會逐漸降低,那麼在排除價格因素之後,全外顯子測序和全基因組測序在檢測外顯子突變方面究竟誰更加強大呢?來自美國的科學家對這一問題進行了相關研究,其研究結果發表在著名國際學術期刊PNAS上。
研究人員指出,全外顯子測序(WES)是對具有蛋白編碼功能的外顯子進行的測序技術,近年來全外顯子測序在發現外顯子基因突變方面逐漸得到廣泛應用,但全基因組測序(WGS)也越來越成為發現外顯子基因突變的一項非常具有吸引力的測序技術。目前,全基因組測序比全外顯子測序價格昂貴,但全基因組測序的價格應該會比全外顯子測序下降得更快。
研究人員利用6個無關聯個體的基因組比較了全外顯子測序和全基因組測序。他們對WES捕獲的一段基因區域分別利用WES和WGS進行內單核苷酸突變(SNV)和小片段插入/缺失突變(indel)檢測,結果顯示WES檢測到的SNV和小片段插入/缺失突變的平均數為84,192和13,325,而WGS檢測到的平均數為84,968和12,702。研究人員對SNV和indel的coverage depth,genotype quality和minor read ratio等參數的分布進行了評估,結果發現全基因組測序的結果更加均一。研究人員發現WGS和WES兩種技術能檢測出絕大多數SNV和indel,但利用WGS能夠檢測出大約650個高質量編碼基因SNV(佔編碼基因突變的3%左右),而利用WES則錯失了這些SNV。最後,研究人員還發現利用WES檢測拷貝數突變(CNV)得到的結果並不可靠。
這項研究表明,雖然目前全基因組測序的價格高於全外顯子測序,但全基因組測序在檢測導致疾病發生的潛在基因突變方面更加強大,尤其是SNV檢測方面。(生物谷Bioon.com)
Whole-genome sequencing is more powerful than whole-exome sequencing for detecting exome variants
Aziz Belkadia,b,1, Alexandre Bolzec,1,2, Yuval Itanc, Aurélie Cobata,b, Quentin B. Vincenta,b, Alexander Antipenkoc, Lei Shangc, Bertrand Boissonc, Jean-Laurent Casanovaa, and Laurent Abel
We compared whole-exome sequencing (WES) and whole-genome sequencing (WGS) in six unrelated individuals. In the regions targeted by WES capture (81.5% of the consensus coding genome), the mean numbers of single-nucleotide variants (SNVs) and small insertions/deletions (indels) detected per sample were 84,192 and 13,325, respectively, for WES, and 84,968 and 12,702, respectively, for WGS. For both SNVs and indels, the distributions of coverage depth, genotype quality, and minor read ratio were more uniform for WGS than for WES. After filtering, a mean of 74,398 (95.3%) high-quality (HQ) SNVs and 9,033 (70.6%) HQ indels were called by both platforms. A mean of 105 coding HQ SNVs and 32 indels was identified exclusively by WES whereas 692 HQ SNVs and 105 indels were identified exclusively by WGS. We Sanger-sequenced a random selection of these exclusive variants. For SNVs, the proportion of false-positive variants was higher for WES (78%) than for WGS (17%). The estimated mean number of real coding SNVs (656 variants, ?3% of all coding HQ SNVs) identified by WGS and missed by WES was greater than the number of SNVs identified by WES and missed by WGS (26 variants). For indels, the proportions of false-positive variants were similar for WES (44%) and WGS (46%). Finally, WES was not reliable for the detection of copy-number variations, almost all of which extended beyond the targeted regions. Although currently more expensive, WGS is more powerful than WES for detecting potential disease-causing mutations within WES regions, particularly those due to SNVs.