The researchers debated between ‘adults with mild disease’ versus ‘newborn babies with terminal disease’. The former was eventually chosen based on concerns about informed consent. It was felt that parents of terminally-ill babies could be coerced into participation easily. Given that the phase 1 study was not expected to have therapeutic benefits and also carried high risk, adults who were capable of providing their own consents were thought to be more appropriate. ^(13,17)

However, when the gene therapy caused an unexpected response that led to the death of 18-year-old Mr Jesse Gelsinger, many aspects of the study were scrutinised, including its eligibility criteria. It was questioned whether neonates with life-threatening disease should have been selected instead, because: ^(17,18)

• The gene therapy, if effective, is going to be of more benefit to children who could die from severe disease, than adults with only mild symptoms.
  
  
• The stakes or risks are higher for adults with mild disease than for children with terminal disease. Risk being a function of:

Risk from the experimental therapy = 

Probability of harm due to the therapy x Magnitude of harm due to the therapy 

The risks from receiving the experimental therapy was felt to be higher in adults who ‘had something to lose’ (Savulescu, 2011) than in babies who are already at risk of death due to their illness (thus had nothing to lose).

The full inclusion / exclusion criteria of this trial ‘Phase I Study of Adenoviral Vector Mediated Gene Transfer for Ornithine Transcarbamylase in Adults With Partial Ornithine Transcarbamylase Deficiency’ (ClinicalTrials.gov, 1999) can be accessed here.