(Robert Carter for The Washington Post)

The test had become something of an annual ritual. Every year beginning when he turned 45, Thomas Clark Semmes, an IT consultant for the federal government, would visit his internist for a physical. In a standard test of the sensory system that is often part of a physical, the Baltimore doctor would prick the soles of Semmes’s feet with a pin.

“He’d look at me and say, ‘Tell me when you feel it,’ and I’d say ‘I will when I can,’ ” Semmes, now 56, recalled of the pinprick test. Because he never felt anything, he said nothing. “It never really concerned me very much,” he recalled. His doctor would then dutifully jot something in his chart, never exploring it further.

But in 2013, nearly a decade after that first test, a quick evaluation by a podiatrist revealed the reason for his unfeeling feet and provided an explanation for an anatomical oddity in one of Semmes’s close relatives. In retrospect, Semmes wishes he had asked his internist about the lack of sensation, but he assumed it wasn’t important — otherwise, the doctor would have said something. And as Semmes would later learn, not knowing what was wrong had cost him valuable time.

“I definitely wish I’d been diagnosed sooner,” he said. “There are things that could have been done to lessen the impact.”

Before 2013, Semmes never had much reason to think about his feet. He knew he had hammertoes — toes that bend downward at the middle joint as a result of heredity or trauma — as well as extremely high arches, but neither condition was painful or limiting. At least, he thought, he did not have bird legs like his father, whose limbs were so storklike that they were a running family joke. “I had big, muscular legs,” Semmes said.

Semmes had wondered whether his father’s legs contributed to a fall in 2012 that resulted in a broken hip and, a year later, his death at age 87. In the last year of his father’s life, Semmes said, he was struck by his “crazy skinny” legs and by how much his father’s hands shook. But his father was beset by multiple medical problems; no doctors had ever mentioned his legs, nor did they focus much on his hand tremor or his complaints of neuropathy — numbness in his hands, feet and legs.

Numb feet

But in the time between his father’s fall and his death, Semmes had begun to notice that his own feet were increasingly tingly or numb. “I knew it wasn’t normal,” he said, “but I was so busy I didn’t really have time” to pay attention to the problem. Semmes knew he wasn’t diabetic — a common cause of neuropathy — but as the numbness slowly spread, he became convinced that something was wrong.

In August 2013 while doing yoga, Semmes, who had moved from Baltimore to his weekend home on Maryland’s Eastern Shore, felt something in his knee pop. A day later he could barely walk and sought treatment at an emergency room; doctors diagnosed arthritis. An orthopedist he subsequently consulted discovered that Semmes had torn the stabilizing cartilage in his knee known as a meniscus, but not badly enough to require surgery.

Semmes asked him about his long-standing foot numbness.

“He said, ‘Oh you have a little neuropathy,’ ” Semmes recalled the bone specialist telling him. The surgeon didn’t seem concerned or inclined to probe further.

But Semmes decided he needed an answer; he worried that he might have a circulatory disorder. “I felt that if the problem was in my feet, I should go to a podiatrist,” he said. On Sept. 9 he saw Jose DeBorja, who practices in Easton.

After listening to his account of the numbness, which had recently begun affecting his hands, DeBorja examined Semmes’s feet and began making observations aloud. He noted his hammertoes and unusually high arches and then said something that shocked Semmes.

Financial analyst Thomas Clark Semmes couldn't figure out why his feet were persistently numb. (Marcia Semmes)

“I think you have a disease called Charcot-Marie-Tooth,” the podiatrist told Semmes, who had never heard of it. He explained that the disease was degenerative, which “completely freaked me out,” Semmes said. He asked the podiatrist to write the name on a piece of paper.

Charlot-Marie-Tooth (CMT) is a constellation of neurological disorders that affect the peripheral nerves, which lie outside the brain and spinal cord; their function is to transmit messages between the brain and the muscles. The disease affects 1 in 2,500 Americans and occurs when a person inherits at least one defective gene from a parent; the errant gene causes the nerves to slowly degenerate, resulting in a loss of sensation. The disease is named after three physicians, two French and one British, who first described it in 1886.

All forms of the disease — there are 70 — result in muscle atrophy and lead to weakness and a progressive loss of sensation in the arms, legs, hands and feet, usually during adolescence or early adulthood. Some types of CMT occur in infancy, while others may surface in adulthood.

The severity of CMT, for which there is no cure and no effective drug treatment, varies considerably, even among affected members of the same family. Unlike other neurological disorders, it rarely affects the respiratory muscles and is not considered a fatal disease; most people with CMT have a normal life expectancy. Pain ranges from mild to severe and some people maintain mobility through the use of leg braces or other orthopedic devices.

Physical therapy and exercise can be helpful in maintaining mobility longer, particularly when the disease is diagnosed early, as Semmes wishes his had been.

The feet are often affected. Hammertoes and unusually high arches are common physical features, although both are seen in people who have no neurological problems.

DeBorja said that Semmes’s is the only case of CMT he has ever seen in a patient in his 20-year career. He was attuned to it, he said, because one of his professors in podiatry school had the disease and talked about it with his students. “It was always in the back of my mind,” said DeBorja, adding that Semmes’s classic symptoms seemed to point to CMT.

The podiatrist said he isn’t sure why the internist failed to make the diagnosis or to investigate Semmes’s neuropathy further, or why the orthopedist missed it. “Maybe he never looked at his feet,” he said. DeBorja referred Semmes to a neurologist for further testing and treatment.

Moving on

Deeply shaken after seeing DeBorja, Semmes called his wife, Marcia, who immediately began researching the disease online.

“By the time I made the 20-minute drive home, she was convinced I had it — and so was I,” Semmes recalled. “Light bulbs began going off: so that’s why my father’s legs were so skinny and why his hands shook, that sort of thing.” Semmes said it is likely that he inherited the disease from his father, who was never diagnosed.

Semmes first consulted a neurologist at Johns Hopkins Hospital and, more recently, another at the University of Pennsylvania; subsequent testing confirmed that Semmes had CMT Type 1b, one of the most common forms.

Adjusting to the diagnosis was difficult. “For a month I was really depressed,” said Semmes. “I would go on the Internet and of course see the worst cases, and it would scare the heck out of me.” Some patients described severe pain or an inability to walk or even open a door.

“I also became obsessed with people’s gait,” he said, watching to see if maybe they showed signs of the disorder. Many people with CMT have a “foot drop,” a slapping walk that results from an inability to lift the front of the foot.

One day about six weeks after his appointment with DeBorja, Semmes said he was at a dog park near his home. He spotted a woman and approached her, saying, “I notice you walk kind of strange. I walk kind of strange, too.” They began talking, and the woman told him she, too, had CMT and that Semmes should get in touch with a local CMT activist. He did and the woman invited Semmes and his wife to her home. “She gave me all this literature [about the disease] and that’s when I started feeling better,” he said.

Because CMT is hereditary, Semmes, who has no children, told his relatives about his diagnosis. “No one else has it,” he said, including his sister.

Semmes, who turns 57 in August, said he is aware the disease is progressing. “It’s slow but noticeable,” he said. Numbness is moving up his legs and he is struck by the thinning of his wrists and ankles. Since his diagnosis, he has succeeded in losing 25 pounds, which can help retain mobility by decreasing the amount of weight his legs must support.

Because his hands are affected, Semmes now uses voice recognition software on his computer, which he finds a poor substitute for typing.

“Accepting that you have a degenerative disease” is the hardest part of living with CMT, he said.

But getting involved with other patients has proved to be a godsend. Marcia Semmes recently became a communications director for the CMT Association. Semmes has formed a support group for patients in Baltimore and helped organize a fundraiser called the Oxford Biathlon, which raises money for research.

“We’ve found our tribe,” Semmes said.

Submit your solved medical mystery to sandra.boodman@washpost.com. No unsolved cases, please. Read previous mysteries at wapo.st/medicalmysteries.