Tue, Jul 09, 2019 - Page 2 News List

Genome sequencing sheds light on rare Usher syndrome

By Chien Hui-ju and William Hetherington  /  Staff reporter, with staff writer

Members of a National Health Research Institutes research team pose with officials for a group photograph at a news conference in Taipei on Saturday.

Photo: Chien Hui-ju, Taipei Times

A breakthrough in research from the National Health Research Institutes (NHRI) using whole genome sequencing has allowed a man with Usher syndrome, whose condition had not been understood for 22 years, to seek treatment.

Medical researchers worldwide are currently able to make definitive diagnoses in about 30 percent of patients with rare diseases, but the institutes say that rate can be increased to 63 percent through whole genome sequencing.

Physician Huang Chun-jung (黃俊榕) has Usher syndrome, a condition characterized by partial or total hearing loss and vision loss that worsens over time.

However, until last month he was not sure what caused his vision and hearing loss, which is now about 30 percent of what healthy people have, making it impossible to seek treatment.

A breakthrough last month by NHRI means not only can he now seek treatment, but can also rule out the genetic pre-existence of the condition in his elder sister and her daughter, Huang told a news conference on Saturday.

Several thousand rare diseases cannot be easily diagnosed, leaving doctors with no option except to keep trying different treatments to try to find one that works, NHRI Director Liang Kung-yee (梁賡義) told reporters.

Whole genome sequencing can offer these people answers, and the NHRI has set up an online network and is working with civic foundations to help people with rare diseases and their families, he said.

About 7,000 rare diseases have been identified so far, 80 percent of which are hereditary, and of those, 400 can be treated, but they remain hard to diagnose, the institutes said.

About 5 percent of Taiwan’s population suffer from rare diseases, NHRI researcher Tsai Shih-feng (蔡世峯) said.

His research team has conducted whole genome sequencing on 139 of those people and their close family members, and has made definitive diagnoses in 63.3 percent of the patients, he said.

The team’s current four-year research project uses the NovaSeq6000 system and is focused on analyzing patients with immune-system deficiencies, epilepsy, spinocerebellar ataxia, hearing impairment, Rett syndrome and certain speech-related problems, he said.

One patient his team worked with suffered from uncontrollable use of “inappropriate language,” which was affecting his interactions at work, Tsai said.

A doctor had suggested the man might have frontotemporal dementia, but did not have the means to confirm his diagnosis, but genome sequencing showed that the man suffered from a MAPT gene mutation, Tsai said.

The NHRI’s findings will bring new hope to patients with rare diseases who often “feel as if they are adrift at sea with no treatment to rely on,” Foundation for Rare Disorders director Chen Kuan-ju (陳冠如) said.

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