Researchers discover new genetic brain disorder in humans

brain

A newly identified genetic disorder associated with degeneration of the central and peripheral nervous systems in humans, along with the genetic cause, is reported in the April 24, 2014 issue of Cell.

The findings were generated by two independent but collaborative scientific teams, one based primarily at Baylor College of Medicine and the Austrian Academy of Sciences, the other at the University of California, San Diego School of Medicine, the Academic Medical Center (AMC) in the Netherlands and the Yale University School of Medicine.

By performing DNA sequencing of more than 4,000 families affected by , the two research teams independently discovered that a disease marked by reduced brain size and sensory and motor defects is caused by a mutation in a gene called CLP1, which is known to regulate tRNA metabolism in cells. Insights into this rare disorder, the researchers said, may have important implications for the future treatment of more common neurological conditions.

"What we found particularly striking, when considering the two studies together, is that this is not a condition that we would have been able to separate from other similar disorders based purely on patient symptoms or clinical features", said Joseph G. Gleeson, MD, Howard Hughes Medical Institute investigator, professor in the UC San Diego departments of Neurosciences and Pediatrics and at Rady Children's Hospital-San Diego, a research affiliate of UC San Diego. "Once we had the gene spotted in these total of seven families, then we could see the common features. It is the opposite way that doctors have defined diseases, but represents a transformation in the way that medicine is practiced."

Each child tested was affected by undiagnosed neurological problems. All of the children were discovered to carry a mutation in the CLP1 gene and displayed the same symptoms, such as brain malformations, intellectual disabilities, seizures and sensory and motor defects. A similar pattern emerged in both studies, one led by Gleeson, with Murat Gunel, MD, of the Yale University School of Medicine and Frank Baas, PhD, of the Academic Medical Center in the Netherlands, and the other by Josef Penninger and Javier Martinez of the Austrian Academy of Sciences, teamed with James R. Lupski, MD, PhD, of the Baylor College of Medicine.

"Knowing fundamental pathways that regulate the degeneration of neurons should allow us to define new pathways that, when modulated, might help us to protect motor neurons from dying, such as in Lou Gehrig's disease," said Penninger, scientific director of the Institute of Molecular Biotechnology of the Austrian Academy of Sciences.

The CLP1 protein plays an important role in generating mature, functional molecules called transfer RNAs (tRNAs), which shuttle amino acids to cellular subunits called ribosomes for assembly into proteins. Mutations affecting molecules involved in producing tRNAs have been implicated in human neurological disorders, such as pontocerebellar hypoplasia (PCH), a currently incurable neurodegenerative disease affecting children. Although CLP1 mutations have been linked to neuronal death and motor defects in mice, the role of CLP1 in human disease was not known until now.

These scientists performed DNA sequencing on children with neurological problems. Seven out of the more than 4,000 families studied shared an identical CLP1 mutation, which was associated with motor defects, speech impairments, seizures, atrophy and neuronal death.

Bass at the AMC said the neurological condition represents a new form of PCH. "Identification of yet another genetic cause for this neurodegenerative disorder will allow for better genetic testing and counseling to families with an affected child," he said.

In a published paper last year, Gleeson and colleagues identified a different gene mutation for a particularly severe form of PCH, and reported early evidence that a nutritional supplement might one day be able to prevent or reverse the condition.

More information: Cell, Karaca et al.: "Human CLP1 mutations alter tRNA biogenesis affecting both peripheral and central nervous system function." dx.doi.org/10.1016/j.cell.2014.02.058

Cell, Schaffer et al.: "CLP1 Founder Mutation Links tRNA Splicing and Maturation to Cerebellar Development and Neurodegeneration." dx.doi.org/10.1016/j.cell.2014.03.049

add to favorites email to friend print save as pdf

Related Stories

New genetic forms of neurodegeneration discovered

Jan 30, 2014

In a study published in the January 31, 2014 issue of Science, an international team led by scientists at the University of California, San Diego School of Medicine report doubling the number of known causes for the neurod ...

Mutated gene causes nerve cell death

Mar 13, 2013

Researchers identify new mechanism in the onset of incurable nerve disease The British astrophysicist Stephen Hawking is likely to be the world's most famous person living with amyotrophic lateral sclerosis ...

Recommended for you

A nucleotide change could initiate fragile X syndrome

50 minutes ago

Researchers reveal how the alteration of a single nucleotide—the basic building block of DNA—could initiate fragile X syndrome, the most common inherited form of intellectual disability. The study appears ...

Gene clues to glaucoma risk

21 hours ago

Scientists on Sunday said they had identified six genetic variants linked to glaucoma, a discovery that should help earlier diagnosis and better treatment for this often-debilitating eye disease.

Mutation disables innate immune system

Aug 29, 2014

A Ludwig Maximilian University of Munich team has shown that defects in the JAGN1 gene inhibit the function of a specific type of white blood cells, and account for a rare congenital immune deficiency that ...

Study identifies genetic change in autism-related gene

Aug 28, 2014

A new study from Bradley Hospital has identified a genetic change in a recently identified autism-associated gene, which may provide further insight into the causes of autism. The study, now published online in the Journal of ...

NIH issues finalized policy on genomic data sharing

Aug 27, 2014

The National Institutes of Health has issued a final NIH Genomic Data Sharing (GDS) policy to promote data sharing as a way to speed the translation of data into knowledge, products and procedures that improve health while ...

User comments