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DNA Molecule

Decoding cellular signals linked to hypospadias

DNA Molecule

“By advancing our understanding of the genetic causes and the anatomic differences among patients, the real goal of this research is to generate knowledge that will allow us to take better care of children with hypospadias,” Daniel Casella, M.D. says.

Daniel Casella, M.D., a urologist at Children’s National, was honored with an AUA Mid-Atlantic Section William D. Steers, M.D. Award, which provides two years of dedicated research funding that he will use to better understand the genetic causes for hypospadias.

With over 7,000 new cases a year in the U.S., hypospadias is a common birth defect that occurs when the urethra, the tube that transports urine out of the body, does not form completely in males.

Dr. Casella has identified a unique subset of cells in the developing urethra that have stopped dividing but remain metabolically active and are thought to represent a novel signaling center. He likens them to doing the work of a construction foreman. “If you’re constructing a building, you need to make sure that everyone follows the blueprints.  We believe that these developmentally senescent cells are sending important signals that define how the urethra is formed,” he says.

His project also will help to standardize the characterization of hypospadias. Hypospadias is classically associated with a downward bend to the penis, a urethra that does not extend to the head of the penis and incomplete formation of the foreskin. Still, there is significant variability among patients’ anatomy and to date, no standardized method for documenting hypospadias anatomy.

“Some surgeons take measurements in the operating room, but without a standardized classification system, there is no definitive way to compare measurements among providers or standardize diagnoses from measurements that every surgeon makes,” he adds. “What one surgeon may call ‘distal’ may be called ‘midshaft’ by another.” (With distal hypospadias, the urethra opening is near the penis head; with midshaft hypospadias, the urethra opening occurs along the penis shaft.)

“By advancing our understanding of the genetic causes and the anatomic differences among patients, the real goal of this research is to generate knowledge that will allow us to take better care of children with hypospadias,” he says.

Parents worry about lingering social stigma, since some boys with hypospadias are unable to urinate while standing, and in older children the condition can be associated with difficulties having sex. Surgical correction of hypospadias traditionally is performed when children are between 6 months to 1 year old.

When reviewing treatment options with family, “discussing the surgery and postoperative care is straight forward. The hard part of our discussion is not having good answers to questions about long-term outcomes,” he says.

Dr. Casella’s study hopes to build the framework to enable that basic research to be done.

“Say we wanted to do a study to see how patients are doing 15-20 years after their surgery.  If we go to their charts now, often we can’t accurately describe their anatomy prior to surgery.  By establishing uniform measurement baselines, we can accurately track long-term outcomes since we’ll know what condition that child started with and where they ended up,” he says.

Dr. Casella’s research project will be conducted at Children’s National under the mentorship of Eric Vilain, M.D., Ph.D., an international expert in sex and genitalia development; Dolores J. Lamb, Ph.D., HCLD, an established leader in urology based at Weill Cornell Medicine; and Marius George Linguraru, DPhil, MA, MSc, an expert in image processing and artificial intelligence.

Yanxin Pei awarded St. Baldrick’s Foundation Research Grant for Childhood Cancer

Yanxin Pei, Ph.D., assistant professor at the Children’s Research Institute, was a recipient of a $100,000 grant that is being named the “Benicio Martinez Fund for Pediatric Cancer Research Grant” from the St. Baldrick’s Foundation, the largest private funder of childhood cancer research grants in the United States.

Dr. Pei studies medulloblastoma – one of the most common malignant brain tumors in children – and has identified a subpopulation of tumor cells that contribute to metastasis after radiotherapy. Her lab is now determining whether targeting these cells can eliminate or prevent the spread of medulloblastoma, thereby improving the outcome of patients with this disease.

In their latest round of funding, the St. Baldrick’s Foundation awarded 76 grants totaling more than $19.1 million to support physician-scientists studying innovative treatment options in the pediatric cancer space. The grants from St. Baldrick’s deliver on its commitment to support the most promising childhood cancer research and work to provide the best solutions possible for kids. The next St. Baldrick’s grant cycle will be announced in fall 2018.

“At St. Baldrick’s, we focus on funding research that has the best potential of giving kids the healthy childhoods they deserve,” said Kathleen Ruddy, CEO of the St. Baldrick’s Foundation.  “I’m proud to say that we have now funded more than a quarter billion dollars since 2005 to support lifesaving childhood cancer research.

Zhe Han, PhD

Lab led by Zhe Han, Ph.D., receives $1.75 million from NIH

Zhe Han, PhD

A new four-year NIH grant will enable Zhe Han, Ph.D., to carry out the latest stage in the detective work to determine how histone-modifying genes regulate heart development and the molecular mechanisms of congenital heart disease caused by these genetic mutations.

The National Institutes of Health (NIH) has awarded $1.75 million to a research lab led by Zhe Han, Ph.D., principal investigator and associate professor in the Center for Genetic Medicine Research, in order to build models of congenital heart disease (CHD) that are tailored to the unique genetic sequences of individual patients.

Han was the first researcher to create a Drosophila melanogaster model to efficiently study genes involved in CHD, the No.1 birth defect experienced by newborns, based on sequencing data from patients with the heart condition. While surgery can fix more than 90 percent of such heart defects, an ongoing challenge is how to contend with the remaining cases since mutations of a vast array of genes could trigger any individual CHD case.

In a landmark paper published in 2013 in the journal Nature, five different institutions sequenced the genomes of more than 300 patients with CHD and their families, identifying 200 mutated genes of interest.

“Even though mutations of these genes were identified from patients with CHD, these genes cannot be called ‘CHD genes’ since we had no in vivo evidence to demonstrate these genes are involved in heart development,” Han says. “A key question to be answered: How do we efficiently test a large number of candidate disease genes in an experimental model system?”

In early 2017, Han published a paper in Elife providing the answer to that lingering question. By silencing genes in a fly model of human CHD, the research team confirmed which genes play important roles in development. The largest group of genes that were validated in Han’s study were histone-modifying genes. (DNA winds around the histone protein, like thread wrapped around a spool, to become packed into a higher-level structure.)

The new four-year NIH grant will enable Han to carry out the next stage of the detective work to determine precisely how histone-modifying genes regulate heart development. In order to do so, his group will silence the function of histone-modifying genes one by one, to study their function in the fly heart development and to identify the key histone-modifying genes for heart development. And because patients with CHD can have more than one mutated gene, he will silence multiple genes simultaneously to determine how those genes work in partnership to cause heart development to go awry.

By the end of the four-year research project, Han hopes to be able to identify all of the histone-modified genes that play pivotal roles in development of the heart in order to use those genes to tailor make personalized fly models corresponding to individual patient’s genetic makeup.

Parents with mutations linked to CHD are likely to pass heart disease risk to the next generation. One day, those parents could have an opportunity to sequence their genes to learn the degree of CHD risk their offspring face.

“Funding this type of basic research enables us to understand which genes are important for heart development and how. With this knowledge, in the near future we could predict the chances of a baby being born with CHD, and cure it by using gene-editing approaches to prevent passing disease to the next generation,” Han says.