Horizontal scars across their throats, although now fading, remind members of the Block family of what they have been through in the past year. Last summer, doctors at Yale found that this family of cattle farmers from Monroe, Conn., has been passing more than hair and eye color between generations; the family’s 10th chromosome harbors a mutation that causes a rare and severe form of thyroid cancer.

Since this discovery, 13 members of the extended family have been diagnosed with the mutation and 10 have had their thyroids removed. Five of the surgeries took place at Yale-New Haven Hospital (YNHH) under the supervision of Julie Ann Sosa, M.D., assistant professor of surgery.

Sosa, who specializes in thyroid cancer, said that the mutation that the Blocks carry, called MEN2A, is extremely rare and that most families in this country with the condition have been known to researchers for years. Sosa herself follows five such families. “Many endocrinologists go their whole lives without seeing any cases of this mutation,” she said.

But last June, Beverly Block Lewis, 51, learned that she had medullary thyroid cancer. In a very few instances this rare cancer is inherited. “The genetic study we ran came back positive,” said Sosa.

Beverly already had hypothyroidism, a deficiency of thyroid hormone, which she inherited from her mother’s side of the family. The condition was the reason for her routine endocrinology appointments. The family assumed the thyroid cancer would also come from the maternal side.

But testing showed that Beverly inherited her mutation from her father, Burton Block, who was then found to have asymptomatic thyroid cancer. Two of Beverly’s siblings, her son and two nephews were also diagnosed with the mutation. All but 4-year-old nephew Jake already had cancer.

“Every diagnosis was a new blow,” said Alyce Block, Beverly’s mother. “Every time was as hard as the first.”

For Beverly’s recently married son, Aaron Lewis, 28, one of the biggest challenges was thinking about future generations. “Kids that aren’t even born yet are going to be affected,” he said.

Over the next several months, YNHH became like a second home for the family members, who were constantly in and out of the hospital with each successive surgery.

But every operation went well and the family pulled through. After his thyroid surgery, 83-year-old Burton also survived a near-fatal car accident that landed him back at YNHH, just doors away from where his son Dan was recovering from a pulmonary embolism following thyroid surgery.

In August, more than a year after the family’s medical saga began, Burton passed away due to inoperable pancreatic cancer unrelated to the thyroid cancer. “He’s really taught us a tremendous amount about strength and patience,” said Beverly, standing at Burton’s bedside a month before his death. “And the importance of a close-knit family bonding together,” added Alyce.