Subsequent Events	9 Months Ended
Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 11—Subsequent Events Partnership with Catalent, Inc. On November 5, 2020, the Company announced a partnership with Catalent, Inc. (“Catalent”) to support the development and manufacturing of the Company’s gene therapies at Catalent’s Maryland-based gene therapy facilities. License Agreement with Abeona Therapeutics Inc. (Rett) On October 29, 2020, the Company entered into a license agreement (the “Abeona Rett Agreement”) with Abeona pursuant to which the Company obtained an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses under certain patents, know-how and materials originally developed by the University of North Carolina at Chapel Hill, the University of Edinburgh and Abeona to research, develop, manufacture, have manufactured, use, and commercialize licensed products for gene therapy and the use of related transgenes for Rett syndrome. Subject to certain obligations of Abeona, the Company is required to use commercially reasonable efforts to develop at least one licensed product and commercialize at least one licensed product in the United States. In connection with the Abeona Rett Agreement, the Company paid Abeona a one-time upfront license fee of $3.0 million. The Company is obligated to pay Abeona up to $26.5 million in regulatory-related milestones and up to $30.0 million in sales-related milestones per licensed Rett product and high single-digit royalties on net sales of licensed Rett products. Royalties are payable on a licensed product-by-licensed product and country-by-country basis until the latest of the expiration or revocation or complete rejection of the last licensed patent covering such licensed product in the country where the licensed product is sold, the loss of market exclusivity in such country where the product is sold, or, if no licensed product exists in such country and no market exclusivity exists in such country, ten years from first commercial sale of such licensed product in such country. The Abeona Rett Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the agreement for convenience upon specified prior written notice to Abeona. Partnership with Invitae Corporation On October 6, 2020, the Company announced a partnership with Invitae Corporation (“Invitae”) to support Invitae’s Detect Lysosomal Storage Diseases (Detect LSDs) and Behind the Seizure® programs. The partnership is intended to help identify individuals who are eligible for the Company’s Phase 1/2 clinical trial evaluating TSHA-101 in patients with GM2 gangliosidosis and patient identification across the Company’s gene therapy pipeline.

Subsequent Events

9 Months Ended

Sep. 30, 2020

Note 11—Subsequent Events

Partnership with Catalent, Inc.

On November 5, 2020, the Company announced a partnership with Catalent, Inc. (“Catalent”) to support the development and manufacturing of the Company’s gene therapies at Catalent’s Maryland-based gene therapy facilities.

License Agreement with Abeona Therapeutics Inc. (Rett)

On October 29, 2020, the Company entered into a license agreement (the “Abeona Rett Agreement”) with Abeona pursuant to which the Company obtained an exclusive, worldwide, royalty-bearing license, with the right to grant sublicenses under certain patents, know-how and materials originally developed by the University of North Carolina at Chapel Hill, the University of Edinburgh and Abeona to research, develop, manufacture, have manufactured, use, and commercialize licensed products for gene therapy and the use of related transgenes for Rett syndrome.

Subject to certain obligations of Abeona, the Company is required to use commercially reasonable efforts to develop at least one licensed product and commercialize at least one licensed product in the United States.

In connection with the Abeona Rett Agreement, the Company paid Abeona a one-time upfront license fee of $3.0 million. The Company is obligated to pay Abeona up to $26.5 million in regulatory-related milestones and up to $30.0 million in sales-related milestones per licensed Rett product and high single-digit royalties on net sales of licensed Rett products. Royalties are payable on a licensed product-by-licensed product and country-by-country basis until the latest of the expiration or revocation or complete rejection of the last licensed patent covering such licensed product in the country where the licensed product is sold, the loss of market exclusivity in such country where the product is sold, or, if no licensed product exists in such country and no market exclusivity exists in such country, ten years from first commercial sale of such licensed product in such country.

The Abeona Rett Agreement expires on a country-by-country and licensed product-by-licensed product basis upon the expiration of the last royalty term of a licensed product. Either party may terminate the agreement upon an uncured material breach of the agreement or insolvency of the other party. The Company may terminate the agreement for convenience upon specified prior written notice to Abeona.

Partnership with Invitae Corporation

On October 6, 2020, the Company announced a partnership with Invitae Corporation (“Invitae”) to support Invitae’s Detect Lysosomal Storage Diseases (Detect LSDs) and Behind the Seizure® programs. The partnership is intended to help identify individuals who are eligible for the Company’s Phase 1/2 clinical trial evaluating TSHA-101 in patients with GM2 gangliosidosis and patient identification across the Company’s gene therapy pipeline.