CAMBRIDGE, Mass. (TheStreet) -- An advisory panel made up of U.S. government scientists recommended Bluebird Bio(BLUE) - Get Report delay the start of a gene therapy clinical trial in children with the inherited blood disorder beta thalassemia for one to two years until more safety data in adults can be gathered, the company said Tuesday night.

The scientific recommendation to slow down with gene therapy for kids is non binding, so Bluebird's plans to conduct two new studies of its LentiGlobin gene therapy in beta thalassemia patients -- one in adults, the other in kids -- has not changed for now, says Bluebird CEO Nick Leschly.

The two studies were designed in consultation with regulators at the FDA and will allow Bluebird to seek approval for LentiGlobin in beta thalassemia if the results are positive. Unless FDA regulators raise new objections or institutional review boards at proposed clinical trial sites object, Bluebird intends to proceed as planned.

"We respect RAC and the process. RAC took a reasonable position when it comes to dealing with kids. We disagree and believe the decision [to proceed with a gene therapy pediatric study] should be placed in the hands of the institutional review boards, the physicians of patients and their families," said Leschly.

RAC refers to the National Institutes of Health Recombinant DNA Advisory Committee, which reviewed Bluebird's proposed study of Lentiglobin in children with beta thalassemia in a public hearing Tuesday.

Last month, Bluebird announced agreements with U.S. and European regulators on a clinical trial plan to get the LentiGlobin gene therapy approved for beta thalassemia. The FDA wants Bluebird to conduct the two studies mentioned above, each enrolling about 15 patients. European regulators said conditional approval of LentiGlobin might be allowed even earlier based on data coming from two beta thalassemia studies already underway.

Asked to spell out a worst-case scenario stemming from the RAC recommendation, Bluebird's Leschly says enrollment in the children's study might be pushed back slightly until data from the adult study is collected.

The possibility FDA reverses course and tells Bluebird it cannot conduct a gene therapy study in kids with beta thalassemia study at all is almost nil, he adds.

On Saturday, Bluebird will present updated results from one of its ongoing studies in patients with beta thalassemia and sickle cell disease at a European medical conference.

Bluebird shares closed Tuesday at $186.63 but dipped 5% to $177 after the company issued a statement about the RAC recommendation.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.