Stories about: Elizabeth Engle

Tracking the elusive genes that cause strabismus

strabismus genes
(PHOTO: ADOBE STOCK)

Strabismus is a common condition in which the eyes do not align properly, turning inward, outward, upward or downward. Two to four percent of children have some form of it. Some cases can be treated with glasses or eye patching; other cases require eye muscle surgery. But the treatments don’t address the root causes of strabismus, which experts believe is neurologic.

For decades, Elizabeth Engle, MD, in Boston Children’s Hospital’s F.M. Kirby Neurobiology Center, has been studying rare forms of strabismus, such as Duane syndrome, in which strabismus is caused by limited eye movements. Her lab has identified a variety of genes that, when mutated, disrupt the development of cranial nerves that innervate the eye muscles. These genetic findings have led to many insights about motor neurons and how they develop and grow.

More recently, with postdoctoral research fellow Sherin Shabaan, MD, PhD, Engle’s lab has been gathering families with common, non-paralytic strabismus, in which both eyes have a full, normal range of motion yet do not line up properly.

Such “garden variety” forms of strabismus have been much harder to pin down genetically.

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Bad to the bone: New light on the brain’s venous system… and on craniosynostosis

cerebral veins and skull development in a normal child
Normal skull and brain venous development in a young child (courtesy Tischfield et al).

A recent study rocked the neuroscience world by demonstrating what in retrospect seems obvious: the brain has its own lymphatic system to help remove waste. A new study, from the laboratory of Elizabeth Engle, MD, at Boston Children’s Hospital, sheds light on another critical, little-studied part of the brain’s drainage system: the dural cerebral veins that remove and reabsorb excess cerebrospinal fluid.

The story of these vessels, the cover article in the next Developmental Cell, is a great example of lab scientists and physicians joining to make fundamental discoveries in biology. Strangely, critical clues come from children with craniosynostosis, a congenital malformation in which the skull plates fuse together too early in prenatal development, resulting in abnormal head shapes and, often, neurologic complications.

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Science Seen: Disrupted developmental genes cause ‘split brain’

split brain syndrome
The two halves of the brain on the right, from a patient with the DCC mutation, are almost completely disconnected. The mutation — first recognized in worms — prevents axons (nerve fibers) from crossing the midline of the brain by interfering with guidance cues. Image courtesy Ellen Grant, MD, director, Fetal-Neonatal Neuroimaging and Developmental Science Center.

Tim Yu, MD, PhD, a neurologist and genomics researcher at Boston Children’s Hospital, was studying autism genes when he saw something on a list that rang a bell. It was a mutation that completely knocked out the so-called Deleted in Colorectal Carcinoma gene (DCC), originally identified in cancer patients. The mutation wasn’t in a patient with autism, but in a control group of patients with brain malformations he’d been studying in the lab of Chris Walsh, MD, PhD.

Yu’s mind went back more than 20 years. As a graduate student at University of California, San Francisco, he’d conducted research in roundworms, studying genetic mutations that made the worms, which normally move in smooth S-shaped undulations, move awkwardly and erratically.

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The neurology resident that could

Eye muscles, the nerves that control them, and where things go wrong (click to enlarge)

Elizabeth Engle used to wait in peoples’ driveways until midnight, hoping to enroll them in her genetic studies of eye-movement disorders. She landed there by chance: during her neurology residency, she saw a little boy whose eyes were frozen in a downward gaze. Wanting to find a solution to a disorder that others had written off, she talked her way into the muscular dystrophy genetics lab of Alan Beggs and Lou Kunkel at Children’s.

Why muscular dystrophy? That tragic muscle-weakening disease somehow spares the eye muscles. Engle thought if Beggs and Kunkel took her on, she could answer two questions at once – what was protecting the eye muscles in muscular dystrophy, and what had caused the little boy’s fixed gaze and droopy eyelids. Plus, she needed laboratory training to study the samples she’d started gathering. “I didn’t have a PhD and was never officially trained in the lab,” she once said. “I didn’t even know how to make chemical solutions.”

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