The state panel that oversees doctors in Maryland has charged a man with practicing medicine without a license just weeks after his father’s license was suspended for allegedly putting autistic children at risk.

The Maryland Board of Physicians says David Geier worked with his father, Mark Geier, at the Rockville and Owings Mills offices of Genetic Consultants of Maryland, where they used a drug therapy that autism experts say is based on junk science.

The two have built a national following of parents who believe autism is linked to mercury in vaccines, a theory discredited by mainstream medicine. The Geiers developed a treatment using Lupron, a testosterone suppressant approved for prostate cancer and ovarian fibroids. Lupron also is sometimes used in the chemical castration of sex offenders.

In children, the drug is used for “precocious puberty,” which the board said Mark Geier over-diagnosed in autistic children.

J. Steven Wise, an attorney for the Geiers, said Thursday that David Geier “categorically denies the charges.” Mark Geier has appealed his suspension.

Another attorney for the Geiers has said that they are being targeted because of their outspoken views and have not hurt any children. Joseph A. Schwartz III said the treatment may be considered “a crazy therapy, but it works” on especially difficult patients. The lawyers produced affidavits in support of Mark Geier and Lupron therapy from parents of five children reviewed by the board.

The lawyers would not address the specifics of the charges Thursday but have said David Geier works in an “administrative” capacity in the offices. Geier has earned a bachelor’s degree and taken some graduate-level classes.

In a report dated May 16, the board said that David Geier had practiced medicine on a host of patients.

The board has set a hearing for July 6.