Mysterious untreatable fevers once devastated whole families. This doctor discovered what caused them

Dr. Daniel Kastner, right, in his lab in 2018 with Dr. Kalpana Manthiram, a clinical fellow at the National Human Genome Research Institute and a colleague of Kastner.

(CNN)It's an ancient disease that may have evolved to confer protection against the plague -- but until 20 years ago, it had scientists and doctors flummoxed.

They couldn't explain why those afflicted, often in the same family, had recurring fevers, abdominal pain, troublesome rashes and muscle aches. Known as familial Mediterranean fever, the disease often went undiagnosed for years, and it was sometimes fatal.
Unusual in most parts of the world, it was more common in the countries that border the Eastern Mediterranean -- including Turkey and Israel -- where one or two of every 1,000 people have it.
    A similar, but unrelated, mystery fever was initially thought to affect families with Scottish and Irish heritage.
      While these types of periodic fevers, now classed as autoinflammatory disorders, are regarded as rare, they cause misery for those who suffer from them.
      "The pain I felt back then, it moved around. One week the pain was in my leg, and the next week my arm would hurt instead," said Victoria Marklund, 47, a Swedish woman who suffered from TRAPS, or tumor necrosis factor receptor-associated periodic syndrome, a disease first identified in a family of Irish and Scottish descent living in the UK city of Nottingham in 1982.
      Her father and grandfather died prematurely from kidney complications, which were likely a consequence of the undiagnosed disorder.
        Marklund has now received an effective treatment and lives symptom-free -- largely thanks to the work of one US physician and health researcher, Dr. Dan Kastner, a distinguished investigator at the National Institutes of Health who serves as scientific director of the National Human Genome Research Institute.
        The Royal Swedish Academy of Sciences on Monday awarded Kastner