NEW YORK (Reuters Health) - Researchers in the US and Britain have pinpointed a gene they say causes Alstrom syndrome, a rare, inherited disorder that causes obesity, hearing and vision disorders in infants and eventually, premature death.

"If we want to figure out ways to treat disease, we need to know the pathology and nature of the gene, that's the first step," study co-author Dr. Jurgen K. Naggert, a staff scientist at the Jackson Laboratory in Bar Harbor, Maine, told Reuters Health. "One day, we hope to contribute to the understanding of this disease and figure a way out of it."

Alstrom syndrome is an extremely rare hereditary condition that was first identified in 1959. The disorder, affecting only around 170 people worldwide, is usually diagnosed shortly after birth, when babies begin gaining excessive amounts of weight and suffer vision difficulties. There is no treatment and by adulthood, patients can develop life-threatening diabetes, heart and kidney failure.

The researchers at Jackson Laboratory, as well as a second team at Southampton University in the UK, independently studied the genetic makeup of individuals with Alstrom syndrome and family members of those affected by the disorder. Their findings were released in the advance online publication of the journal Nature Genetics.

Both teams of researchers reported they have located a recessive gene on chromosome 2 that seems to be associated with the disease. People who inherit any one of several different mutations on that gene seem to develop the disorder, Naggert said.

Naggert said the gene identified, ALMS1, is not similar to other more well-known genes. "Usually, when you do positional cloning, you hope that the gene has some similarity to one you know," he said. "Unfortunately, this gene is not similar to any other gene, so right now we have no clue about what its function is."

Although the pathways causing the disorder are not clear, the researchers did confirm that the gene affects organs throughout the body associated with the disorder, such as the eyes and the kidney, he said.

The identification of the gene could help doctors properly identify patients suffering from the syndrome, although doctors have been able to diagnose it accurately so far based solely on clinical symptoms.

Naggert also said that by identifying an additional potential pathway associated with obesity, the finding may help lead to a better understanding of what causes obesity in the general population.

"We are pretty sure there are hundreds of obesity genes, that's the reason it has been so difficult to know what causes obesity," he said. "To efficiently treat obesity, we need to know all the pathways that can lead to obesity. This is one more piece of the puzzle, it gives us another entry point."

SOURCE: Nature Genetics advance online publication 2002;10.1038/ng867.

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