英语语法分析

No variant was found in EXT2 gene of this proband.

先证者EXT2基因没有发现变异。

In contrast, direct DNA sequencing requires only a single sample from the proband.

相比之下，直接测序只需要被检测者的血样。

The risk to the sibs of a male proband depends upon the carrier status of the mother.

男性先证者的同胞的患病风险取决于其母亲的携带者状态。