Stories about: microcephaly

Gene mutation in children with microcephaly reveals an essential ingredient for brain development

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This electron microscope image shows two multivesicular bodies in the dendrites of neighboring neurons in the cerebellum of a normal mouse. Each contains vesicles bearing sonic hedgehog. (Michael Coulter/Boston Children’s Hospital)

In 2012, researchers in the Boston Children’s Hospital lab of Christopher Walsh, MD, PhD, reported a study of three unrelated families that had children with microcephaly. All had smaller-than-normal brains — both the cerebrum and the cerebellum were reduced in size— and all had mutations that knocked out the function of a gene called CHMP1A.

It was clear that CHMP1A is needed for the brain to grow to its proper dimensions. But the study stopped there.

“Then I came along, and my goal was to figure out what this gene is doing in brain during development, and why, when you lose it, you have a small brain,” says Michael Coulter, MD, PhD, who joined the Walsh lab as a student in 2012. …

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Mutant ferrets and kids with microcephaly shed light on brain evolution

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ASPM, ferrets, microcephaly and brain evolution
Fawn Gracey illustration

Mouse brains are tiny and smooth. Ferret brains are larger and convoluted. And ferrets, members of the weasel family, could provide the missing link in understanding how we humans acquired our big brains.

Children with microcephaly, whose brains are abnormally small, have a part in the story too. Microcephaly is notorious for its link to the Zika virus, but it can also be caused by mutations in various genes. Some of these genes have been shown to be essential for growth of the cerebral cortex, the part of our brain that handles higher-order thinking.

Reporting in Nature today, a team led by Christopher A. Walsh, MD, PhD, of Boston Children’s Hospital and Byoung-Il Bae, PhD, at Yale University, inactivated the most common recessive microcephaly gene, ASPM, in ferrets. This replicated microcephaly and allowed the team to study what regulates brain size.

“I’m trained as a neurologist, and study kids with developmental brain diseases,” said Walsh in a press release from the Howard Hughes Medical Institute, which gave him a boost to his usual budget to support this work. “I never thought I’d be peering into the evolutionary history of humankind.” …

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Galloway-Mowat mutations have dual target: kidney cells, neurons

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Evidence of disease in GAMOS patients
Disease phenotype of GAMOS patients. Left: Kidney cells show signs of nephrotic syndrome. Right: Anomalies in brain development

With the help of more than 100 clinical collaborators around the world, Friedhelm Hildebrandt, MD has received thousands of blood samples from patients with nephrotic syndrome. They have helped Hildebrandt’s lab determine several underlying causes of this serious kidney disorder, in which high levels of protein are expelled in the urine.

“Nephrotic syndrome is not one disease; in fact, we already know that it is 55 different diseases,” says Hildebrandt, chief of the Division of Nephrology at Boston Children’s Hospital.

Over the course of time, Hildebrandt’s lab has discovered 35 of the more than 55 genes that can cause nephrotic syndrome. Identifying the different genetic pieces of the puzzle can help tailor a precision medicine approach to treating patients.

The latest piece, published earlier this month in Nature Genetics, is a set of four single-gene mutations that cause Galloway-Mowat syndrome (GAMOS) a rare disorder causing early-onset nephrotic syndrome and, often, microcephaly (abnormally small head size). Until now, the genetic changes underlying GAMOS and why they affect two disparate organs — the brain and kidney — have not been well understood.  …

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Tracking Zika? Use HealthMap

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Like a virus, the story of Zika virus in the Americas is evolving very, very rapidly. Just in the last week we’ve seen:

To help public health investigators, policy makers, epidemiologists and others keep up with the virus, the team at HealthMap has released a dedicated Zika virus tracking resource at http://www.healthmap.org/zika/. The new map brings in Zika-related information and news from a variety of sources in near real-time, and includes a constantly updated interactive timeline of the virus’s explosive spread across South and Central America.

The HealthMap team is also providing regularly updated coverage of the Zika virus outbreak on their Disease Daily blog.

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Q&A: Mosquitos, Zika virus and microcephaly in Brazil

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mosquito-Thriving

As you may have heard, Brazil is facing a startling outbreak of microcephaly, a rare condition in which a child is born with a head and brain that are much smaller than normal. Microcephaly is almost always associated with neurologic impairment and can be life-threatening.

The epidemic has been linked to an influx of the mosquito-borne virus Zika, first detected in Brazil last April. This past Friday, January 16, the Centers for Disease Control and Prevention issued travel warnings advising pregnant women to avoid visiting El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela and Puerto Rico. And over the weekend, the first U.S. case of microcephaly linked to Zika reportedly surfaced in Hawaii.

Why this virus, why now? And how can a virus affect someone’s head size? In this Q&A on our sister blog, Thriving, Ganeshwaran Mochida, MD, of Boston Children’s Brain Development and Genetics (BrDG) Clinic, who specializes in microcephaly, and Asim Ahmed, MD, an infectious disease specialist at Boston Children’s, offer their insights.

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Saving Grace: A whodunit solved with clues from the Middle East

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microcephaly
Microcephaly causes small head size, seizures, developmental delays and intellectual disabilities. Did the Lennons’ unborn child have it?

Addison Lennon met all her early milestones: she sat up on time, crawled on time and walked on time.  At about 4 months, however, she had a seizure, and her parents started to worry. By 9 months, her head appeared small for her age.

Her neurologist reassured the family that Addison could still be within the lowest 5 percent of the normal range. “We were thinking she was typical,” says Kari Lennon, “she would be in that 5 percent.”

At 15 months, however, Addison had another seizure that was a lot more severe.  She had been tested for everything.  No one could pinpoint the cause of her so-called microcephaly, or small head.

Kari spent countless hours online in search of answers.  “How I could fix Addie? How could I make her better?” (Read on, or watch this video:)

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