genome

Genes are the building blocks of inheritance. Passed from parent to child, they contain instructions for making proteins. If genes don't produce the right proteins or don't produce them correctly, a child can have a genetic disorder.

Gene therapy is an experimental technique that uses genes to treat or prevent disease. The most common form of gene therapy involves inserting a normal gene to replace an abnormal gene. Other approaches include:

• Swapping an abnormal gene for a normal one
• Repairing an abnormal gene
• Altering the degree to which a gene is turned on or off

Although there is much hope for gene therapy, it is still experimental.

Genes are the building blocks of heredity. They are passed from parent to child. They hold DNA, the instructions for making proteins. Proteins do most of the work in cells. They move molecules from one place to another, build structures, break down toxins, and do many other maintenance jobs.

Sometimes there is a mutation, a change in a gene or genes. The mutation changes the gene's instructions for making a protein, so the protein does not work properly or is missing entirely. This can cause a medical condition called a genetic disorder.

You can inherit a gene mutation from one or both parents. A mutation can also happen during your lifetime.

There are three types of genetic disorders:

• Single-gene disorders, where a mutation affects one gene. Sickle cell anemia is an example.
• Chromosomal disorders, where chromosomes (or parts of chromosomes) are missing or changed. Chromosomes are the structures that hold our genes. Down syndrome is a chromosomal disorder.
• Complex disorders, where there are mutations in two or more genes. Often your lifestyle and environment also play a role. Colon cancer is an example.

Genetic tests on blood and other tissue can identify genetic disorders.

NIH: National Library of Medicine

Cloning describes the processes used to create an exact genetic replica of another cell, tissue or organism. The copied material, which has the same genetic makeup as the original, is referred to as a clone. The most famous clone was a Scottish sheep named Dolly.

There are three different types of cloning:

• Gene cloning, which creates copies of genes or segments of DNA
• Reproductive cloning, which creates copies of whole animals
• Therapeutic cloning, which creates embryonic stem cells. Researchers hope to use these cells to grow healthy tissue to replace injured or diseased tissues in the human body.

NIH: National Human Genome Research Institute

Your family history includes health information about you and your close relatives. Families have many factors in common, including their genes, environment, and lifestyle. Looking at these factors can help you figure out whether you have a higher risk for certain health problems, such as heart disease, stroke, and cancer.

Having a family member with a disease raises your risk, but it does not mean that you will definitely get it. Knowing that you are at risk gives you a chance to reduce that risk by following a healthier lifestyle and getting tested as needed.

You can get started by talking to your relatives about their health. Draw a family tree and add the health information. Having copies of medical records and death certificates is also helpful.

Centers for Disease Control and Prevention

Genetic counseling provides information and support to people who have, or may be at risk for, genetic disorders. A genetic counselor meets with you to discuss genetic risks. The counseling may be for yourself or a family member. Or you may get it when you are planning or expecting a baby. You may follow up with genetic testing.

There are many reasons to seek genetic counseling. You may consider it if you :

• Have a personal or family history of a genetic condition or birth defect
• Are pregnant or planning to be pregnant after age 35
• Already have a child with a genetic disorder or birth defect
• Have had two or more pregnancy losses or a baby who died
• Have had ultrasound or screening tests that suggest a possible problem

Genetic testing is a type of medical test that looks for changes in your DNA. DNA is short for deoxyribonucleic acid. It contains the genetic instructions in all living things. Genetic tests analyze your cells or tissue to look for any changes in:

• Genes, which are parts of DNA that carry the information needed to make a protein
• Chromosomes, which are thread-like structures in your cells. They contain DNA and proteins.
• Proteins, which do most of the work in your cells. Testing can look for changes in the amount and activity level of proteins. If it finds changes, it might be due to changes in your DNA.

Genetic testing may be done for many different reasons, including to:

• Find genetic diseases in unborn babies. This is one type of prenatal testing.
• Screen newborn babies for certain treatable conditions
• Lower the risk of genetic diseases in embryos that were created using assisted reproductive technology
• Find out if you carry a gene for a certain disease that could be passed on to your children. This is called carrier testing.
• See whether you are at increased risk of developing a specific disease. This may be done for a disease that runs in your family.
• Diagnose certain diseases
• Identify genetic changes that may be causing or contributing to a disease that you were already diagnosed with
• Figure out how severe a disease is
• Help guide your doctor in deciding the best medicine and dosage for you. This is called pharmacogenomic testing.

Genetic tests are often done on a blood or cheek swab sample. But they may also be done on samples of hair, saliva, skin, amniotic fluid (the fluid that surrounds a fetus during pregnancy), or other tissue. The sample is sent to a laboratory. There, a lab technician will use one of several different techniques to look for genetic changes.

The benefits of genetic testing include:

• Helping doctors make recommendations for treatment or monitoring
• Giving you more information for making decisions about your health and your family's health:
  • If you find out that you are at risk for a certain disease, you might take steps to lower that risk. For example, you may find out that you should be screened for a disease earlier and more often. Or you might decide to make healthy lifestyle changes.
  • If you find out that you are not at risk for a certain disease, then you can skip unnecessary checkups or screenings
  • A test could give you information that helps you make decisions about having children
• Identifying genetic disorders early in life so treatment can be started as soon as possible

The physical risks of the different types of genetic testing are small. But there can be emotional, social, or financial drawbacks:

• Depending on the results, you may feel angry, depressed, anxious, or guilty. This can be especially true if you are diagnosed with a disease that does not have effective treatments.
• You may be worried about genetic discrimination in employment or insurance
• Genetic testing may give you limited information about a genetic disease. For example, it cannot tell you whether you will have symptoms, how severe a disease might be, or whether a disease will get worse over time.
• Some genetic tests are expensive, and health insurance might only cover part of the cost. Or they may not cover it at all.

The decision about whether to have genetic testing is complex. In addition to discussing the test with your health care provider, you can meet with a genetic counselor. Genetic counselors have specialized degrees and experience in genetics and counseling. They can help you understand the tests and weigh the risks and benefits. If you do get a test, they can explain the results and make sure that you have the support that you need.

Your newborn infant has screening tests before leaving the hospital. There may be different tests depending on the state where you live. They include:

• Tests on a few drops of blood from pricking the baby's heel. The tests look for inherited disorders. All states test for at least 30 of these conditions.
• A hearing test that measures the baby's response to sound
• A skin test that measures the level of oxygen in the blood. This can tell if the baby has a congenital heart defect.

These tests look for serious medical conditions. If not treated, some of these conditions can cause lifelong health problems. Others can cause early death. With early diagnosis, treatment can begin right away, before serious problems can occur or become permanent.

If a screening shows that your baby might have a condition, the health care provider or the state health department will call you. It is important to follow up quickly. Further testing can verify whether your baby has the condition. If so, treatment should start right away.

NIH: National Institute of Child Health and Human Development

A rare disease is one that affects fewer than 200,000 people in the United States. There are nearly 7,000 rare diseases. More than 25 million Americans have one.

Rare diseases:

• May involve chronic illness, disability, and often premature death
• Often have no treatment or not very effective treatment
• Are frequently not diagnosed correctly
• Are often very complex
• Are often caused by changes in genes

It can be hard to find a specialist who knows how to treat your rare disease. Disease advocacy groups, rare disease organizations, and genetics clinics may help you to find one.

NIH: National Institutes of Health

It seems to happen almost every day - you hear about the results of a new medical research study. Sometimes the results of one study seem to disagree with the results of another study.

It's important to be critical when reading or listening to reports of new medical findings. Some questions that can help you evaluate health information include:

• Was the study in animals or people?
• Does the study include people like you?
• How big was the study?
• Was it a randomized controlled clinical trial?
• Where was the research done?
• If a new treatment was being tested, were there side effects?
• Who paid for the research?
• Who is reporting the results?

NIH: National Institutes of Health

Alpha-1 antitrypsin deficiency (AAT deficiency, or AATD) is an inherited condition that raises your risk for lung and liver disease. If you have this condition, your body doesn't make enough alpha-1 antitrypsin (AAT).

AAT is made by your liver. It helps protect your lungs from inflammation and irritating substances you might breathe in, such as smoke. If your liver doesn't make enough AAT, your lungs may be more easily damaged from smoking, pollution, or dust from the environment. This can lead to a serious lung condition called chronic obstructive pulmonary disease (COPD). AAT deficiency may also cause a liver disease called cirrhosis. This is more common in children who have AAT deficiency.

AAT deficiency is a genetic disorder. That means it's caused by changes in your genes, which may also be called gene variants or mutations.

Your genes carry information that controls what you look like and how your body works. AAT deficiency is caused by changes in the SERPINA1 gene, which carries instructions for making the AAT protein. These gene changes are inherited from your parents, so AAT deficiency tends to run in families:

• If you have two mutated copies of the gene, it means you have a condition called AAT deficiency. People with this disorder have a higher risk of getting lung disease or liver damage before the age of 45.
• If you have one mutated copy of the gene, you are a carrier of AAT deficiency. In these cases, this means you are at slightly higher risk of developing lung disease, especially if you have other risk factors, such as being a smoker. You could still pass the mutated gene on to your children.

There are a few gene changes that cause AAT deficiency. These gene changes can:

• Decrease the amount of AAT protein your liver makes.
• Prevent your liver from making any AAT.
• Affect the shape of the AAT protein so that it can't move out of your liver to protect your lungs. Over time, AAT builds up in your liver and causes damage.

Some people who have AAT deficiency do not have any symptoms. For those who do, symptoms usually appear in people between 20 and 50 years old. These symptoms may include:

• Wheezing
• Shortness of breath, especially after exercise
• Chronic cough with phlegm (mucus)
• Repeated respiratory infections such as colds and the flu
• Chest pain
• Fatigue
• Faster-than-normal heartbeat when you stand up
• Vision problems
• Losing weight without trying

Some people who have AAT deficiency may have liver damage. Signs of liver damage include jaundice (a condition that causes your skin and eyes to turn yellow) and swelling in your legs.

Rarely, AAT deficiency can cause skin problems, such as painful lumps or patches.

Your health care provider may test you for AAT deficiency if you have:

• Symptoms of AAT deficiency
• A condition that could be related to AAT deficiency
• Relatives who have AAT deficiency
• Relatives who have a lung or liver disease that could be related to AAT deficiency

AAT deficiency in babies often affects the liver. Your baby may need AAT testing if he or she has signs of liver disease such as jaundice or abnormal liver enzyme tests.

A blood test can check the level of AAT protein in your blood. If the level is lower than normal, it is likely that you have AAT deficiency.

A genetic test is the most certain way to check for AAT deficiency and should be done to confirm the results of the blood test. There are two types of genetic tests:

• A genotype test looks for the more common types of gene changes that can cause AAT deficiency.
• A phenotype test checks for changes in the AAT protein that change how it would normally work.

If your lungs are affected, you may also have lung function tests to see how well your lungs are working.

There is no cure for AAT deficiency, but there are treatments to help with the symptoms and slow the lung damage it causes. Treatment options may include:

• Inhaled medicines to help you breathe better.
• Pulmonary rehabilitation.
• Oxygen therapy.
• Augmentation therapy, which is a lifelong treatment. It raises the levels of the AAT protein in your lungs, using ATT protein taken from the blood of donors. It helps slow down lung damage. It cannot prevent liver damage.
• Lung surgery or a lung transplant, if your lungs are severely damaged.
• Liver transplant, if your liver is severely damaged.

To help prevent or delay lung damage, it is important to quit smoking (if you smoke) and avoid secondhand smoke, dust, and air pollution. Ask your provider If you need to stop drinking alcohol.