A Retrospective Study of Subjects With Thymidine Kinase 2 Deficiency

A Retrospective Study of Subjects With Thymidine Kinase 2 Deficiency Treated With the Combination of Pyrimidine Nucleos(t)Ides as Well as Untreated Subjects to Collect Vital Status Data and Supporting Information

This is a multicenter, multinational, retrospective chart-review study to evaluate survival in patients with Thymidine Kinase 2 deficiency (TK2d).

This is a retrospective, chart-review study. The primary goal is to use data on survival and other related information to support a comprehensive evaluation of patients with Thymidine Kinase 2 deficiency (TK2d) who have not been treated with pyrimidine nucleos(t)ides including deoxycytidine monophosphate/deoxythymidine monophosphase (dCMP/dTMP), and deoxycytidine/deoxythymidine (dC/dT), and/or MT1621(dC/dT), and those that have received one or more of these treatments. The secondary goals of this study will focus on describing the participant's clinical course and treatment experience.

Inclusion Criteria:

1. Signed informed consent by the subject or parent(s)/LAR and/or assent by the subject (when applicable), unless the associated IRB or EC provides an appropriate consent waiver that allows review of medical records for this study.
2. Confirmed genetic mutations in the TK2 gene.
3. Availability of medical records or information pertaining to vital status at a minimum.

Exclusion Criteria:

Not applicable as this is a non-interventional study.