Studies Say Sequencing of Patients' Genomes Offers New Hope

Newly published studies say that US researchers have decoded the entire genome of patients to identify the root cause of their diseases paving the way towards individual genomic treatments.

James Lupski of Baylor College of Medicine in Houston, Texas, sequenced his own genome to locate the gene responsible for the rare neurological disorder he suffers from, Charcot-Marie-Tooth syndrome.

Although not life threatening, the disorder affects nerve function in the body's limbs, hands and feet, leading to trouble walking and frequently to deformation of the feet.

"This is the first time we have tried to identify a disease gene this way," Lupski, vice chair of molecular and human genetics at Baylor College of Medicine.

"It demonstrates that the technology is robust enough that we can find disease genes by determining the whole genome sequence," he said.

He said the technology can now be used "to interpret the clinical information in the context of the sequence of the hand of cards you have been dealt. Isn't that the goal or dream of personalized genomic medicine?"

Lupski's research, published online Wednesday in the New England Journal of Medicine, identified several inherited mutations in copies of the gene SH3TC2 in his genome sequence.

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Although his parents did not have Charcot-Marie-Tooth syndrome, four of their children had the mutations and the disease.

"I have the disease and I have two mutant genes," said Lupski. "I know I have a genetically-recessive disease and I've known that for 40 years."

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With his research team, Lupski first identified the copy of a gene linked to Charcot-Mariet-Tooth syndrome in 1991.

Since then, researchers have discovered mutations in at least 40 genes implicated in the syndrome but none responsible for the form of the syndrome affecting Lupski and his brothers and sisters.

The second study, published Thursday by the online journal Science Express and carried out by the Institute for Systems Biology in Seattle, sequenced the genome of a family four.

It confirmed the role played by four genes in two rare diseases affecting two children -- Miller syndrome, which is characterized by facial and limb malformations, and Primary Ciliary Dyskinesia (PCD), which affects tiny hairlike structures that move mucus out of the airwaves.

The parents had no genetic abnormality but each carried a recessive gene that resulted in their son and daughter acquiring the two extremely rare diseases.

The research was launched in hopes of finding clinical genomic applications for the treatment of cancer or Alzheimer's and comes seven years after the first human genome sequence was completed in 2003 at a cost of 500 million dollars.

Since then at least 10 human genomes have been sequenced and all were of people in good health.

Technological advances make it possible to sequence the genome of a sick person at a more reasonable cost -- about 50,000 dollars -- and with results that are precise enough to have clinical uses.

"We hope we can use the information about you and your genome in your care," said Lupski.

"If you have hypertension, can we use your genome to figure out a better treatment for you? It will take a lot of time. We don't know what 90 percent of the genes in the genome do."

Source-AFP
RAS