Researchers uncover mutant gene

Barb Sweet
Published on September 16, 2012
Nancy Merner, a native of Paradise, contributed to the breakthrough discovery surrounding a rare genetic disease affecting people connected to this province. She is shown in the Research Centre Guy Rouleau Laboratory in Montreal. — Submitted photo

When postdoctoral research fellow Nancy Merner began work a few years ago at the Research Centre Guy Rouleau Laboratory in Montreal, she was embarking on research close to her heart.

Merner is from Paradise, and contributed to a genetic breakthrough involving a rare disease in this province. Results of the study were announced recently by Centre Hospitalier de l’Université de Montréal (CHUM), where the lab is located.

The discovery of the mutant gene, said Merner, could help researchers solve other genetic mysteries affecting different diseases.

“This is just the beginning. What else does it cause?” Merner said.

Researchers from the Rouleau Laboratory affiliated with the CHUM Research Centre and the CHU–Sainte-Justine Research Centre discovered the genetic cause of a rare disease reported only in patients originating from Newfoundland — hereditary spastic ataxia (HSA).

Merner said the disease can be difficult to diagnose, but those who suffer from it all share the same genetic marker.

For those affected, the discovery will allow genetic testing to aid the diagnosis and identify those at risk.

The disease applies to people living outside this province as well as inside, due to outmigration, Merner noted.

“Adults can make realistic choices on careers. Families have the option to have prenatal screening,” she said.

“Anything that could help prevent or cure this disease, the genetic discovery is the first step to that.”

The condition is characterized by lower-limb stiffness and lack of co-ordination. The co-ordination problems lead to difficulties with speech and swallowing, and eye movement abnormalities.

According to CHUM, the disease is not deadly, but those affected start developing gait problems between the ages of 10 and 20, walk with a cane in their 30s, and in the most severe cases, need to use a wheelchair in their 50s.

HSA is transmitted from the affected parent to the child, with a 50 per cent chance of the child having the mutation.

Researchers and clinicians from Memorial University contacted Rouleau, who is also a professor of medicine at the Université de Montréal, more than a decade ago to investigate the genetics behind this disorder occurring in three large Newfoundland families on the Avalon Peninsula — more than 100 individuals with a common ancestor.

Inge Meijer, a former doctoral candidate in the Rouleau Laboratory, discovered these families were ancestrally related, and in 2002, identified the locus (DNA region) containing the mutation causing HSA.

A few years later, Cynthia Bourassa, lead author of the study, took over Meijer’s project and new technology has aided the latest work.

Bourassa, a master’s student in the faculty of medicine at the Université de Montréal, teamed up with Merner.

The authors say the mutation in the gene may affect neurotransmission in areas of the nervous system where the synaptobrevin protein is located, causing the unique symptoms of HSA. There are not enough messengers released, so nerves cannot function optimally.

Those involved in the research are in the process of informing family members.

“It’s very important to relay the findings back,” Merner said. “They will be offered future genetic tests for this.”