Nav: Home

Gene behind long-recognized mitochondrial disease has highly varied effects

March 12, 2019

Philadelphia, March 12, 2019--For more than two decades, mutations in a gene located in the DNA of mitochondria have been classified as a mitochondrial disease and linked to a particular set of symptoms. However, according to new findings from researchers at Children's Hospital of Philadelphia (CHOP), mutations in this gene, which encodes an essential part of the mitochondrial motor known as ATP synthase that generates cellular energy, are much more variable than previously thought. This prompts the need to develop more precise clinical tests that can better determine the course of treatment for patients affected by mitochondrial disorder. The study was published online on February 14 in the journal Human Mutation.

Mitochondria are structures found within human and animal cells that are responsible for energy production. Mitochondria contain 37 genes encoded in their own DNA (mtDNA) that are separate from the DNA found inside the nucleus of the cell. Variations in more than 350 different genes located across both nuclear and mitochondrial DNA are responsible for causing mitochondrial diseases, which can typically cause more than 16 different symptoms in each patient and affect multiple organs.

Mutations in the mtDNA-encoded ATP synthase membrane subunit 6 gene (MT-ATP6) are found in between 10 and 20 percent of cases of Leigh syndrome, a progressive brain disorder long recognized as a form of mitochondrial disease, and another recognizable condition known as neuropathy, ataxia, and retinitis pigmentosa (NARP) syndrome.

"We went into this study wanting to look at the more than 200 reported cases of mitochondrial disease with a MT-ATP6 mutation to better understand the clinical presentation of its many variants," said study leader Rebecca Ganetzky, MD, an attending physician in the Mitochondrial Medicine Frontier Program at CHOP, and an assistant professor of Pediatrics in the Perelman School of Medicine at the University of Pennsylvania. "Patients with an MT-ATP6 mutation not only vary significantly in what symptoms they develop, but there has also been extensive variability in biochemistry analyses of their cells and tissues, making it difficult to apply any sort of universal diagnostic or treatment strategy for these patients."

Ganetzky and her colleagues reviewed all of the 218 published cases of MT-ATP6 mitochondrial disease to-date to assess their variants and compare those findings with clinical and biochemical features of the disease. The authors also presented a new clinical case series of 14 additional patients with MT-ATP6 variants of uncertain significance or relation to their medical problems.

What the researchers ultimately found was that despite those having one common mutation, this is a particularly heterogeneous disease in terms of the sequence variations and clinical symptoms that may occur. The study identified a total of 34 variants within the MT-ATP6 mutation, where surprisingly no single biochemical feature was shared by all individuals with these variants.

"This study provides an important point of reference for patients in whom MT-ATP6 variants are discovered in diagnostic testing, as we now recognize just how variable this disease may be," Ganetzky said. "We need to develop better ways to test for this disease, since the classical clinical syndromic presentations of NARP and Leigh syndrome are not sufficient to capture the problems present in all of these patients."

Ganetzky said that future studies are needed to systematically evaluate the functional significance for all of the MT-ATP6 variants. The authors recommend a multi-pronged approach to assessing biochemical diversity, including development of a common community resource of all gene variants along with their biochemical and clinical features. Additionally, a project supported by the National Institutes of Health is under way led by CHOP Mitochondrial Medicine Frontier Program executive director, Marni J. Falk, MD, to expertly curate MT-ATP6 variants that cause Leigh syndrome. CHOP also offers and continues to investigate a variety of advanced testing techniques for mitochondrial disease, including those that will help better understand mitochondrial energy production effects in patients with MT-ATP6 variants.
-end-
This study was supported by grants from the National Institutes of Health (HD093484, DK113250, HD086984), the United Mitochondrial Disease Foundation and the North American Mitochondrial Disease Foundation. Co-authors include Elizabeth McCormick, Amy C. Goldstein, Zarazuela Zokipli-Cunningham, and Marni J. Falk in the CHOP Mitochondrial Medicine Frontier Program, and colleagues from Ludwig Maximilians University of Munich in Germany.

Ganetzky et al, "MT-ATP6 mitochondrial disease variants: Phenotypic and biochemical features analysis in 218 published cases and cohort of 14 new cases" Human Mutation, online Feb. 14, 2019. doi.org/10.1002/humu.23723

About Children's Hospital of Philadelphia: Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals, and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country. In addition, its unique family-centered care and public service programs have brought the 564-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu

Children's Hospital of Philadelphia

Related Dna Articles:

A new spin on DNA
For decades, researchers have chased ways to study biological machines.
From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.
Self-healing DNA nanostructures
DNA assembled into nanostructures such as tubes and origami-inspired shapes could someday find applications ranging from DNA computers to nanomedicine.
DNA design that anyone can do
Researchers at MIT and Arizona State University have designed a computer program that allows users to translate any free-form drawing into a two-dimensional, nanoscale structure made of DNA.
DNA find
A Queensland University of Technology-led collaboration with University of Adelaide reveals that Australia's pint-sized banded hare-wallaby is the closest living relative of the giant short-faced kangaroos which roamed the continent for millions of years, but died out about 40,000 years ago.
More Dna News and Dna Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...