April 2022
Beginner to intermediate
486 pages
10h 22m
Chinese
Content preview from 云端基因组学
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
210
｜
第
7
章
继续学习下节之前，若先休息一会儿，可考虑关闭虚拟机，以便在你享受生
活的时候不必为闲置计算资源白费钱。
7.3
体细胞拷贝数变异
前面我们一直专心于小型变异、
SNV
和
InDel
的研究。它们的特点是，与参考序列
相比，特定核苷酸出现或缺失。而讲到拷贝数变异，我们的思路要来个大转弯（方
法也迥异！），因为我们将探究目标样本中的序列相对于目标样本自身的量（图
7-5
和图
7-6
）。换言之，我们并非实际度量生物材料出现的拷贝数，而是度量拷贝率，
我们以此为代理，因为它是拷贝数变异（
CNA
）的后果。该过程我们还将使用参考
基因组，主要是将其作为坐标系统，以便定义那此展示
CNA
的片段。
如图
7-5
所示，拷贝数是每个基因座（
locus
，如基因或其他有意义的
NDA
片段）
拷贝的绝对数量，其值为整数。拷贝率则是每个基因座的拷贝数与平均倍数的相对
比率，其值为实数。
拷贝数
拷贝率
重复
三染色体性
二倍体生物的
染色体
（染色单体形式）
图
7
-
5
：拷贝数和拷贝率的区别
图
7-6
展示的是一个所有染色体具有预期拷贝数的正常细胞系（左）和一个发生多
处主要
CNA
变异的癌细胞系（右）的对比，其差别惊人，更不必提多种结构性变异。
对于图
7-6
中的正常细胞系（确实大都是健康的人类细胞），任意给定染色体的拷
贝数为
2
，且其拷贝率为
1
。而癌细胞系染色体变动很大，例如，染色体
7
的拷贝数
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.