He opens the door to the space where Whitney has spent most of the last decade.
Whitney lies motionless on a simple bed, his head shaved and his frame emaciated. He's fed by a tube directly into his stomach. His lips haven't uttered a word in five years.
Davis, who is 77, leads a lab that invented much of the technology that powered the Human Genome Project
. Now he and his wife spend much of their days caring for their 35-year-old son, who is immobilized by myalgic encephalomyelitis, or chronic fatigue syndrome (ME/CFS)
Sunday is ME/CFS International Awareness Day. There is no cure. But Davis is leading a global push to root out the molecular basis of what is laying waste to Whitney and millions of other sufferers around the world so that scientists can better treat the disease.
Davis signals to his wife, Janet Dafoe, that Whitney is ready. She goes in and wipes her son's face. She pulls the covers up toward his head while he lies motionless.
She fixes an IV bag to a pole, which will drip water into her son's veins.
Davis sinks to his knees and takes Whitney's socks off. He clips his son's toenails. He washes his son's feet.
For the couple, it's a holy moment.