Research Update

Medical Research Update
Ellen Burns, Vice President and Medical Liaison

Last year we announced in the DFI Newsletter that the gene causing HSN I (the Deater Disease) had been identified and confirmed by research teams in Australia and Massachusetts. The researchers studied 12 families and identified three different mutations in the gene. Everyone who had one of the mutations in the gene had the disease. This was fantastic news! Armed with this knowledge, scientists can now begin to look for the fundamental reasons for the cause of the nerve damage.

Each cell in the human body contains all the information needed to make a whole person. This information is stored in the nucleus of the cell in material called DNA. Each person inherits half his DNA from his mother and half from his father. There are millions of ways the combinations of DNA can be put together, making each person unique. The DNA is arranged into chromosomes, and organized on the chromosomes into genes. Genes make proteins, and proteins make enzymes.

Genes control how the body looks and functions. The chemical building blocks of a gene can be likened to the letters in a word. Like children’s letter blocks, each block represents a specific letter. If one of the blocks, or letters, is out of place the whole word, or gene, can be altered. For example, CAT can become HAT.

Just as a sentence containing an incorrect word will make no sense, the cell doesn’t recognize the incorrect “word.” For example, “The hat jumped onto the table.” The “bad” protein, produced by the affected half of the gene, isn’t recognized, and isn’t working. The “good” protein is produced by the gene that comes from the parent who doesn’t have the disease. Usually this is not a problem, because we usually make much more of the protein than we need.

But something else is happening at the same time. The “bad” protein produces an inhibiting effect on the “good” protein. When the “good” protein works to make an enzyme, the “bad” protein interferes. So the result is that there is a decrease in enzyme activity.

In the Deater Disease, the gene SPTLC1 tells the cells to make one part of the serine palmitoyltransferase enzyme. This enzyme is expressed (produced) in every cell in the body. This enzyme is known to affect the production of a fatty substance (glycosyl ceramide) in the body. This substance belongs to a class of fats known as sphingolipids. Sensory nerves seem particularly sensitive to decreased amounts of sphingolipids.

Research needs to be done to determine if giving nerve cells more sphingolipids will prevent damage to those cells. Other possibilities are that the “bad” protein may affect the cell in other ways that we don’t yet understand. The Deater Foundation hopes to continue to support such research until a cure is found!