Subsequent Events	9 Months Ended
Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Note 12 — Subsequent Events Acquisition of Option to License Worldwide Rights to Clinical-Stage AAV9 Gene Therapy Program for CLN7 Disease In October 2021, the Company announced its exclusive option to license the worldwide rights to a clinical-stage AAV9 gene therapy program for the treatment of CLN7, a form of Batten disease. The first-generation construct for the CLN7 program was developed in the laboratory of Steven Gray, Ph.D., Associate Professor at UT Southwestern Chief Scientific Advisor for the Company. The CLN7 program is currently in a Phase 1 clinical proof-of-concept trial run by UT Southwestern, and the Company expects the availability of preliminary human proof-of-concept clinical safety and efficacy data from the first-generation construct by year-end 2021. The Company also entered into a research collaboration with UT Southwestern to develop a next-generation construct for the treatment of CLN7 disease, which is expected to improve potency, safety profile, packaging efficiency and manufacturability over the first-generation construct. Completion of the next-generation construct design is anticipated by year-end 2021 with commercial-grade GMP material expected in 2022. The Company intends to initiate a planned pivotal trial using the next-generation construct in 2022, with reference to the human proof-of-concept clinical data being generated from the first generation construct. Sales Agreement On October 5, 2021, the Company entered into a Sales Agreement (the “Sales Agreement”) with SVB Leerink LLC and Wells Fargo Securities, LLC (collectively, the “Sales Agents”), pursuant to which the Company may issue and sell, from time to time, shares of its common stock having an aggregate offering price of up to $150.0 million through the Sales Agents. The Sales Agents may sell common stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) of the Securities Act, including sales made directly on or through the Nasdaq Global Select Market or any other existing trade market for the common stock, in negotiated transactions at market prices prevailing at the time of sale or at prices related to prevailing market prices, or any other method permitted by law. The Sales Agents will be entitled to receive 3.0% of the gross sales price per share of common stock sold under the Sales Agreement. As of the date of these financial statements, no shares of common stock have been issued and sold pursuant to the Sales Agreement.

Subsequent Events

9 Months Ended

Sep. 30, 2021

Note 12 — Subsequent Events

Acquisition of Option to License Worldwide Rights to Clinical-Stage AAV9 Gene Therapy Program for CLN7 Disease

In October 2021, the Company announced its exclusive option to license the worldwide rights to a clinical-stage AAV9 gene therapy program for the treatment of CLN7, a form of Batten disease. The first-generation construct for the CLN7 program was developed in the laboratory of Steven Gray, Ph.D., Associate Professor at UT Southwestern Chief Scientific Advisor for the Company. The CLN7 program is currently in a Phase 1 clinical proof-of-concept trial run by UT Southwestern, and the Company expects the availability of preliminary human proof-of-concept clinical safety and efficacy data from the first-generation construct by year-end 2021. The Company also entered into a research collaboration with UT Southwestern to develop a next-generation construct for the treatment of CLN7 disease, which is expected to improve potency, safety profile, packaging efficiency and manufacturability over the first-generation construct. Completion of the next-generation construct design is anticipated by year-end 2021 with commercial-grade GMP material expected in 2022. The Company intends to initiate a planned pivotal trial using the next-generation construct in 2022, with reference to the human proof-of-concept clinical data being generated from the first generation construct.

Sales Agreement

On October 5, 2021, the Company entered into a Sales Agreement (the “Sales Agreement”) with SVB Leerink LLC and Wells Fargo Securities, LLC (collectively, the “Sales Agents”), pursuant to which the Company may issue and sell, from time to time, shares of its common stock having an aggregate offering price of up to $150.0 million through the Sales Agents. The Sales Agents may sell common stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) of the Securities Act, including sales made directly on or through the Nasdaq Global Select Market or any other existing trade market for the common stock, in negotiated transactions at market prices prevailing at the time of sale or at prices related to prevailing market prices, or any other method permitted by law. The Sales Agents will be entitled to receive 3.0% of the gross sales price per share of common stock sold under the Sales Agreement. As of the date of these financial statements, no shares of common stock have been issued and sold pursuant to the Sales Agreement.