Table 1.

Assays to characterize nuclease on-target activity.

	Mutation detection assay with CEL-I/T7EI	RFLP Gel Assay	Fluorescent Gene Addition	Traffic Light Reporter	Single Cell Clone Analysis	NextGen Sequencing	SMRT Sequencing
Measures HDR	No	Yes	Yes	Yes	Yes	Yes	Yes
Highly Sensitive (<2%)	No	No	Yes	Yes	Possible	Yes	Yes
Measures NHEJ	Yes	No	No	Yes	Yes	Yes	Yes
Uses Clinically Applicable Donor DNA	Not relevant	Yes	No	No	Yes	Yes	Yes
Measures Endogenous Locus	Yes	Yes	Yes	No	Yes	Yes	Yes
High-Throughput	Moderate	Moderate	Yes	Yes	No	Yes	Yes
Allows Long Homology Arms	Not relevant	Yes	Yes	Yes	Yes	No	Yes

In defining “clinically applicable” donor DNA, we refer to a donor molecule that is free of elements unapproved for human application (such as fluorescent proteins) and is homologous to the therapeutic gene target (not an artificial reporter locus).