Janet Davison Rowley

As a child stamp collector, Janet Rowley pored over intricate images, seeking an extra curlicue or letter that would enhance a stamp’s value. Her ability to discern perturbations in expected patterns prepared her to notice deviant human chromosomes
decades later.

Logic and orderliness appealed to Rowley and lured her toward science, an interest that led to medicine. Medical school quotas for women—three out of a class of 65—excluded
Rowley from admission the first time she applied. She patiently waited an extra year.

The day after Rowley graduated, she married another medical student. Committed to having children and staying home with them, she decided to work part time. She would
pursue clinical medicine—and later, research—in this fashion while raising four sons. During that period, she made her first key discoveries.

Rowley went to Oxford for her husband’s sabbatical in 1961–1962. She couldn’t practice medicine there, so she decided to study chromosomes, which had snagged her interest when she learned that Down syndrome arises from an extra chromosome 21. By year’s end, she was hooked on research. She came home, dreamed up a $5000-per-year, part-time job that gave her access to a microscope and a darkroom, and convinced Leon Jacobson at the University of Chicago to provide these resources.

In 1960, Peter Nowell and David Hungerford had noticed an abnormally small chromosome in cells from patients with chronic myeloid leukemia (CML). Its consistent presence prompted them to speculate that the genetic peculiarity instigates the disease. This proposal met skepticism, as cancer triggers genetic havoc in cells: Many scientists thought that the odd chromosome resulted from—rather than caused—malignancy.

Before 1970, scientists could discern the approximate size and shape of human chromosomes, but many looked similar. Then cytologists developed methods that reveal dark and light bands that render chromosomes distinguishable. Rowley aimed
these techniques at white blood cells from CML patients and discovered that the missing material from the tiny chromosome, number 22, had not vanished as many scientists thought, but reappeared on the end of chromosome 9. This pattern emerged early in disease, which supported the theory that the aberration promotes cellular misbehavior. Based on this work and similar findings that linked a different chromosomal rearrangement to another cancer, Rowley championed the notion that particular translocations, as such DNA exchanges are called, cause specific malignancies, an idea that has earned wide experimental support.

Subsequent studies showed that chromosome 22 and chromosome 9 had swapped genetic material. More than a decade later, scientists demonstrated that the tail of a gene from chromosome 9 that fosters cell division had fused to the head of a gene on chromosome 22—and lost its molecular brakes in the process. Rowley’s work has transformed our understanding of many cancers, improving diagnosis and unleashing powerful new treatments.

Author: Evelyn Strauss, Ph.D.