Study inclusion and exclusion criteria
| Number | Category | Description |
| Inclusion criteria | ||
| IC-1 | Publication year | 2012–2018 |
| IC-2 | Publication type | Full-text articles in peer review journals |
| IC-3 | Publication quality | Full text article should include clear objective, methodology, analysis/discussion, conclusion and a defined set of references. |
| IC-4 | Type of medicine | Including but not limited to gene therapy |
| IC-5 | Outcomes | Full text article should include at least one challenge related to patient access |
| Exclusion criteria | ||
| EC-1 | Language | Articles not in English |
| EC-2 | Publication type | Book, book chapters, News articles/press release, congress abstracts/posters |