The following common disorders come with varying degrees of genetic risk. That risk, if it is known, can sometimes be lessened through preventive measures. Other times, it cannot. In these cases, the results of a genetic test can, like a boomerang, lead nowhere and so their value is questionable.
About one in four people in industrialized countries are affected by hypertension, which increases the risk of heart attack and stroke by as much as 40 percent.
At least 10 genetic variants are known to predispose individuals to hypertension. The most studied are the angiotensinogen (AGT), adducin and angiotensinogen-converting enzyme (ACE) genes.
Low sodium intake, drug therapy, smoking cessation.
Affects five to 10 percent of the population; figures are increasing.
Scientists have associated about 10 regions on the genome with this disorder, but have not identified any specific genes.
Exterminate household mites, the most common environmental factor causing syptoms to appear.
NON INSULIN-DEPENDENT (TYPE 2) DIABETES
Affects one in 10 people older than age 65.
Researchers have recently identified variants of a susceptibility gene in chromosome 2 (CAPN10). Another 10 regions of the genome are associated with the disorder.
Sports, diet, smoking cessation
INSULIN DEPENDENT (TYPE 1 OR JUVENILE)
Autoimmune disease. Affects one to three in 1,000 people under the age of 20.
HLA variants DR3 and DR4 increase the risk 15-fold. Another 15 regions in the genome probably contain predisposing genes.
Prevention No prevention is currently available.
One in five people older than age 80 and 6 to 10 in 100 people older than age 75 are affected.
People carrying two copies of the E4 version of the apolipoprotein (Apo) gene have ten times the risk of developing Alzheimers as do those with other Apo variants. Rare familial forms are due to mutations in the presenilin (PS1) or amyloid protein (APP) genes.
No prevention is currently available. An immunotherapy is under study.
Affects one in eight women in the U.S. About 10 percent of all cases are genetic in origin.
Hundreds of predisposing mutations have been found in the genes BRCA1 and BRCA2. Women with these mutations have an increased probability (up to 85 percent) of developing breast cancer.
Three options are currently available: surveillance using mammograms and clinical breast exams; chemoprevention using drugs such as tamoxifen and ramoxifen; or the surgical removal of healthy breasts and/or ovaries.
From two to 10 in 10,000 children are affected.
Researchers beleive that a region on chromosome 7, and perhaps another on chromosome 15, are associated with the disease.
No prevention is currently available.
Five to 10 percent of all cases are hereditary in origin.
People carring mutations in genes MLH1 or MSH2 are at very high risk.
Regular colonoscopies can reduce the risk by more than 60 percent.
MULTIPLE ENDOCRINE NEOPLASIA
Rare tumor of the thyroid gland
People carrying mutations in the oncogene RET face virtually a 100 percent chance of developing the condition.
Surgical removal of thyroid gland.
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