Genome sequencing holds great potential for diagnosing diseases, finding treatments and ultimately cutting medical costs, experts say, but insurance companies are leery of covering the still-new procedure, preventing it so far from becoming a routine part of medical care.

Boston-based Partners HealthCare is one of just two systems in the country to offer full genome sequencing for clinical patients. The out-of-pocket cost of unlocking your full genetic code, though, is steep: $9,000.

“Cost is a barrier,” said Heidi Rehm, chief laboratory director at the Partners Center for Personalized Genetic Medicine in Cambridge.

The lab started offering full genome sequencing last August — using blood samples to extract information from DNA — but it has done the complex analysis for fewer than half a dozen patients since then. Insurance companies didn’t cover the costs for any of those patients, Rehm said.

For patients suffering from a range of diseases, from cancer to hearing loss, sequencing can help identify the gene causing the problem and help doctors determine which treatments will be most effective. Genetic sequencing can also tell patients if they’re at risk of developing certain conditions later in life.

The challenge for scientists like Rehm is to prove that this kind of analysis is useful not just for sick patients but for healthy ones.

“Can I say every patient should get their genome sequenced? We just don’t have the collective evidence and the studies to prove that today,” Rehm said. “So the insurers are not going to cover everything today.”

Insurance companies do pay for some genetic tests — those that test specifically for a patient’s risk of developing breast cancer, for example — but they’re still evaluating the benefit of full genome sequencing, which involves much more data and analysis.

“We don’t have a lot of information yet to make sweeping decisions,” said Dr. Neil Minkoff, medical director for the Massachusetts Association of Health Plans. “We tend to look at the individual patient or individual physician’s request. It’s still early in our experience with it.”

The state’s three largest insurers, Blue Cross Blue Shield, Harvard Pilgrim Health Care and Tufts Health Plan, did not respond to requests for comment.

While touting genome sequencing, scientists acknowledge its limits. Currently, 99 percent of genetic information is still not understood, said Dr. Christine Seidman, director of the Biomedical Research Institute at Brigham and Women’s Hospital. “There’s far more information than we can make sense of,” she said.

But with the information they understand now, scientists can answer important questions, like whether a patient was correctly diagnosed.

“The medical necessity of knowing we are correct in the diagnosis I think is important for the insurers to understand,” she said. “It’s better for the patient.”

As the cost of sequencing comes down, Rehm said she expects every baby will have his or her genome sequenced within five to 10 years.