Werner syndrome is characterized by the dramatic, rapid appearance of features associated with normal aging. Individuals with this disorder typically grow and develop normally until they reach puberty. Affected teenagers usually do not have a growth spurt, resulting in short stature. The characteristic aged appearance of individuals with Werner syndrome typically begins to develop when they are in their twenties and includes graying and loss of hair; a hoarse voice; and thin, hardened skin. They may also have a facial appearance described as "bird-like." Many people with Werner syndrome have thin arms and legs and a thick trunk due to abnormal fat deposition.

As Werner syndrome progresses, affected individuals may develop disorders of aging early in life, such as cloudy lenses (cataracts) in both eyes, skin ulcers, type 2 diabetes, diminished fertility, severe hardening of the arteries (atherosclerosis), thinning of the bones (osteoporosis), and some types of cancer. It is not uncommon for affected individuals to develop multiple, rare cancers during their lifetime. People with Werner syndrome usually live into their late forties or early fifties. The most common causes of death are cancer and atherosclerosis.

Mutations in the WRN gene cause Werner syndrome. The WRN gene provides instructions for producing the Werner protein, which is thought to perform several tasks related to the maintenance and repair of DNA. This protein also assists in the process of copying (replicating) DNA in preparation for cell division. Mutations in the WRN gene often lead to the production of an abnormally short, nonfunctional Werner protein. Research suggests that this shortened protein is not transported to the cell's nucleus, where it normally interacts with DNA. Evidence also suggests that the altered protein is broken down more quickly in the cell than the normal Werner protein. Researchers do not fully understand how WRN mutations cause the signs and symptoms of Werner syndrome. Cells with an altered Werner protein may divide more slowly or stop dividing earlier than normal, causing growth problems. Also, the altered protein may allow DNA damage to accumulate, which could impair normal cell activities and cause the health problems associated with this condition.

Normal Function

The WRN gene provides instructions for producing the Werner protein, which plays a critical role in repairing damaged DNA. The Werner protein functions as a type of enzyme called a helicase. Helicase enzymes generally unwind and separate double-stranded DNA. The Werner protein also functions as an enzyme called an exonuclease. Exonucleases trim the broken ends of damaged DNA by removing DNA building blocks (nucleotides). Research suggests that the Werner protein first unwinds the DNA and then removes abnormal DNA structures that have been accidentally generated.

Overall, the Werner protein helps maintain the structure and integrity of a person's DNA. This protein plays an important role in copying (replicating) DNA before cell division and transferring the information in genes to the cell machinery that makes proteins (transcription). Additionally, recent studies suggest that the Werner protein may be particularly important for maintaining DNA at the ends of chromosomes (telomeres).

Health Conditions Related to Genetic Changes

Werner syndrome

More than 60 mutations in the WRN gene are known to cause Werner syndrome. Most of these mutations result in an abnormally short, nonfunctional Werner protein. Research suggests that this shortened protein is not transported into the cell's nucleus, where it normally interacts with DNA. Furthermore, the shortened protein is broken down more quickly than the normal Werner protein, reducing the amount of this protein in the cell. Without normal Werner protein in the nucleus, DNA replication, repair, and transcription are disrupted. Researchers are still determining how mutations in the WRN gene lead to the signs and symptoms of Werner syndrome.

Prostate cancer

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Cancers

Some changes to a person's genes are acquired during that person's lifetime and are present only in certain cells. These differences, called somatic changes, are not inherited. Somatic changes in the WRN gene are found in nonhereditary tumors and involve a process called methylation. Methylation is a chemical modification that attaches small molecules called methyl groups to certain segments of DNA. When too many methyl groups are attached to the WRN gene (hypermethylation), the gene is turned off and the Werner protein is not produced. Without this protein, cells do not respond normally to DNA damage. The lack of Werner protein allows mutations to accumulate in other genes, which may cause cells to grow and divide in an uncontrolled way. This kind of unregulated cell growth can lead to the formation of cancerous tumors. Hypermethylation of the WRN gene has been found in many different types of tumors, including colon, rectal, lung, stomach, prostate, breast, and thyroid tumors.

Other Names for This Gene

• RECQ3
• RECQL2
• RECQL3
• Werner syndrome
• Werner Syndrome helicase
• Werner syndrome protein
• Werner syndrome, RecQ helicase-like
• WRN_HUMAN

Genomic Location

Werner syndrome is inherited in an autosomal recessive pattern. All individuals inherit two copies of each gene. To have Werner syndrome, a person must have a mutation in both copies of the WRN gene in each cell. There is nothing either parent can do, before or during pregnancy, to cause a child to have this.

People with autosomal recessive conditions inherit one mutation from each of their parents. The parents, who each have one mutation, are known as carriers. Carriers of an autosomal recessive disorder typically do not have any signs or symptoms (they are unaffected). When two carriers of an autosomal recessive condition have children, each child has a:

• 25% (1 in 4) chance to have the disorder
• 50% (1 in 2) chance to be an unaffected carrier like each parent
• 25% (1 in 4) chance to be unaffected and not be a carrier

The signs and symptoms of Werner syndrome do not usually appear until the teens. This first sign may be slower than normal growth during puberty. In the 20s-30s, other signs of early aging appear. Some of the signs and symptoms of Werner syndrome include:

• Shorter than average height as an adult
• Bilateral cataracts (clouding of the lens of both eyes )
• Premature graying and thinning of the hair on the head
• Skin changes (thinning of skin, fragile skin)
• Loss of fat under the skin
• Thin limbs
• Characteristic facial changes (pinched nose, narrow face)
• Voice changes
• Decreased functioning of the testes and ovaries
• Decreased fertility
• Open skin sores, especially on the ankles
• Narrowing and hardening of the arteries (atherosclerosis)
• Type 2 diabetes mellitus
• Thinning of the bones (osteoporosis)
• Cancer

Not everyone with Werner syndrome will have all of these symptoms.