In a field of long, yellow grass, a young woman is lying on the ground, gazing at a farmhouse on an idyllic summer day.
This is Andrew Wyeth's 1948 painting 'Christina's World,' one of the most famous paintings in American history, which hangs in the Museum of Modern Art in New York.
But this lovely image has a dark side.
The subject in the painting is Christina Olson, Wyeth's good friend and neighbour. For most of her life, she suffered from a mysterious disorder, which slowly took away her ability to walk, and eventually to use her hands.
She died at the age of 74 after a difficult life, and her disease has never been diagnosed.
After closely examining a range of evidence about her condition, Mayo Clinic child neurologist Marc Patterson has pinpointed a diagnosis. He thinks she likely had an early-onset form of Charcot-Marie-Tooth Disease, a group of inherited disorders that affect the peripheral nerves and can lead to significant problems with movement.
"This was a fascinating case," he says. "This painting has long been a favorite of mine, and the question of Christina's ailment was an intriguing medical mystery. I think her case best fits the profile of this disease."
The diagnosis has been presented at the 23nd annual Historical Clinicopathological Conference at the University of Maryland School of Medicine.