A Boston University doctor with a history of butting heads with the establishment is irking child abuse specialists nationwide by testifying in defense of parents accused of maltreatment — claiming that a rare genetic disease, not parental wrongdoing, is leading to children’s bone fractures.

Dr. Michael F. Holick’ testimony — currently at issue in a child abuse case in Maine — is prompting concern among pediatricians who say he has no scientific proof to back up his claims and is providing covers to potentially dangerous parents putting children further at risk.

“This false controversy makes it hard to protect the children,’’ said Robert Sege, a Boston child abuse specialist and member of the American Academy of Pediatrics’ Committee on Child Abuse and Neglect.

Holick, a professor of medicine at BU’s school of medicine and director of the Bone Health Care Clinic at Boston Medical Center, said he is confident from decades of working with families with Ehlers-Danlos syndrome, that the disorder can lead to bone fractures. He said that although he is not a pediatrician or a child abuse expert, future medical studies will prove him correct.

“Just because you see fractures doesn’t mean it’s child abuse,’’ he said. “Prosecutors are very unhappy with me and child abuse experts are very upset with me.”

The dispute is scheduled to be aired publicly Friday night as part of an ABC News 20/20 story about a Maine couple’s claim that Ehlers-Danlos, not abuse, caused the injuries to their two-month-old son, Ryder Ross. The father, Brandon Ross, was indicted last year on 12 counts of child abuse and is awaiting trial in Sagadahoc County, Maine.

Prosecutors declined to comment and the Rosses could not be reached for comment.

Holick, better known for his research into Vitamin D deficiencies that can cause bone disorders, is not one to shy from controversy. In 2004, he was asked to resign from Boston University’s department of dermatology because he recommended that people expose themselves to some sunlight to increase their body’s natural Vitamin D production. He also was criticized at the time for accepting funding from a nonprofit arm of the Indoor Tanning Industry.

Holick said he first saw a connection between Ehlers-Danlos and fractured bones over two decades ago working with teenagers and adults. He said he first testified on behalf of people accused of abuse about five years ago, helping a Massachusetts couple win an acquittal.

He says he receives calls nationwide from frantic parents like the Rosses and provides his testimony on a pro-bono basis. Already, he has provided expert testimony in two dozen cases, the majority of which have resulted in acquittals, he said. Just last month, a Utah judge ruled in favor of parents accused of abusing their infant who had multiple bone fractures in different stages of healing, stating that there was no “clear and convincing evidence” that the child was abused.

David Coleman, chair of Boston University’s Department of Medicine, said he was unable to comment on the doctors’ dispute.

But Holick’s defense is prompting concern in the medical field. Stephen C. Boos, medical director for the Family Advocacy Center at Baystate Children’s Hospital in Springfield, said some children could be returned to dangerous parents because of a defense that isn’t based in science.

We are creating out of nothing a defensive strategy,” he said. “Of course it concerns me.”

Sege, also interviewed by ABC, said Holick has slim credentials to make a connection between Ehlers-Danlos and fractures in children.

He said Holick has not published any peer-reviewed research that links the genetic disease to bone fractures in infants and is gaining a following nationwide precisely because nobody else sees this link. Indeed, he argues that there is not even a genetic test that can adequately prove that a person has the disease, much less whether it leads to bone fractures.

Sege said he doesn’t know the details of the Ross case, but that often juries and others don’t want to believe the sad truth that “babies really are abused.”