Health Topics

Genetics birth defects

Genetic Counseling
National Library of Medicine

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

Genetics Home Reference


Genetic Counseling
Pregnancy and Reproduction
Genetics/Birth Defects
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 ...
Birth Defects
National Library of Medicine
Abnormalities

A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. One out of every 33 babies in the United States is born with a birth defect.

A birth defect may affect how the body looks, works or both. Some birth defects like cleft lip or neural tube defects are structural problems that can be easy to see. To find others, like heart defects, doctors use special tests. Birth defects can range from mild to severe. Causes can include

  • Genetics
  • Exposures to medicines or chemicals. For example, alcohol abuse can cause fetal alcohol syndrome.
  • Infections during pregnancy
  • Certain medicines. Before you get pregnant, talk to your health care provider about any medicines you take.
  • Not getting enough of certain nutrients. For example, not getting enough folic acid before and during pregnancy is a key factor in causing neural tube defects.

For most birth defects, the cause is unknown.

Health care providers can diagnose certain birth defects during pregnancy, with prenatal tests. That's why it important to get regular prenatal care. Other birth defects may not be found until after the baby is born. Sometimes the defect is obvious right away. Other times, the health care provider may not discover it until later in life.

Babies with birth defects often need special care and treatments. The treatments may include surgery, medicines, assistive devices, and therapies.

Centers for Disease Control and Prevention


Congenital Abnormalities
Genetics/Birth Defects
A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. ...
Prenatal Testing
National Library of Medicine
Amniocentesis
Chorionic Villi Sampling
Fetal Ultrasound

Prenatal testing provides information about your baby's health before he or she is born. Some routine tests during pregnancy also check on your health. At your first prenatal visit, your health care provider will test for a number of things, including problems with your blood, signs of infections, and whether you are immune to rubella (German measles) and chickenpox.

Throughout your pregnancy, your health care provider may suggest a number of other tests, too. Some tests are suggested for all women, such as screenings for gestational diabetes, Down syndrome, and HIV. Other tests might be offered based on your

  • Age
  • Personal or family health history
  • Ethnic background
  • Results of routine tests

There are two types of tests:

  • Screening tests are tests that are done to see if you or your baby might have certain problems. They evaluate risk, but do not diagnose problems. If your screening test result is abnormal, it does not mean that there is a problem. It means that more information is needed. Your health care provider can explain what the test results mean and possible next steps. You may need diagnostic testing.
  • Diagnostic tests show whether or not you or your baby have a certain problem.

It is your choice whether or not to get the prenatal tests. You and your health care provider can discuss the risks and benefits of the tests, and what kind of information the tests can give you. Then you can decide which ones are right for you.

Dept. of Health and Human Services Office on Women's Health


Prenatal Diagnosis
Pregnancy and Reproduction
Genetics/Birth Defects
Diagnostic Tests
Female Reproductive System
Prenatal testing provides information about your baby's health before he or she is born. Some routine tests during pregnancy also check on your health. At your ...
Genetic Disorders
National Library of Medicine
Progeria

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


Genetic Diseases, Inborn
Genetics/Birth Defects
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 ...
Genes and Gene Therapy
National Library of Medicine
Human Genome Project

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.

Genetics Home Reference


Genetic Therapy
Genes
Genetics/Birth Defects
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 ...
Neurofibromatosis
National Library of Medicine
von Recklinghausen's Disease
Recklinghausen's disease

Neurofibromatosis is a genetic disorder of the nervous system. It mainly affects how nerve cells form and grow. It causes tumors to grow on nerves. You can get neurofibromatosis from your parents, or it can happen because of a mutation (change) in your genes. Once you have it, you can pass it along to your children. Usually the tumors are benign, but sometimes they can become cancerous.

There are three types of neurofibromatosis:

  • Type 1 (NF1) causes skin changes and deformed bones. It usually starts in childhood. Sometimes the symptoms are present at birth.
  • Type 2 (NF2) causes hearing loss, ringing in the ears, and poor balance. Symptoms often start in the teen years.
  • Schwannomatosis causes intense pain. It is the rarest type.

Doctors diagnose the different types based on the symptoms. Genetic testing is also used to diagnose NF1 and NF2. There is no cure. Treatment can help control symptoms. Depending on the type of disease and how serious it is, treatment may include surgery to remove tumors, radiation therapy, and medicines.

NIH: National Institute of Neurological Disorders and Stroke


Neurofibromatoses
Cancers
Brain and Nerves
Genetics/Birth Defects
Neurofibromatosis is a genetic disorder of the nervous system. It mainly affects how nerve cells form and grow. It causes tumors to grow on nerves. You can get neurofibromatosis ...
Huntington's Disease
National Library of Medicine
HD
Huntington's chorea

Huntington's disease (HD) is an inherited disease that causes certain nerve cells in the brain to waste away. People are born with the defective gene, but symptoms usually don't appear until middle age. Early symptoms of HD may include uncontrolled movements, clumsiness, and balance problems. Later, HD can take away the ability to walk, talk, and swallow. Some people stop recognizing family members. Others are aware of their environment and are able to express emotions.

If one of your parents has Huntington's disease, you have a 50 percent chance of getting it. A blood test can tell you if have the HD gene and will develop the disease. Genetic counseling can help you weigh the risks and benefits of taking the test.

There is no cure. Medicines can help manage some of the symptoms, but cannot slow down or stop the disease.

NIH: National Institute of Neurological Disorders and Stroke


Huntington Disease
Brain and Nerves
Genetics/Birth Defects
Huntington's disease (HD) is an inherited disease that causes certain nerve cells in the brain to waste away. People are born with the defective gene, but symptoms ...
Tay-Sachs Disease
National Library of Medicine

Tay-Sachs disease is a rare, inherited disease. It is a type of lipid metabolism disorder. It causes too much of a fatty substance to build up in the brain. This buildup destroys nerve cells, causing mental and physical problems. .

Infants with Tay-Sachs disease appear to develop normally for the first few months of life. Then mental and physical abilities decline. The child becomes blind, deaf, and unable to swallow. Muscles begin to waste away and paralysis sets in. Even with the best of care, children with Tay-Sachs disease usually die by age 4.

The cause is a gene mutation which is most common in Eastern European Ashkenazi Jews. To get the disease, both parents must have the gene. If they do, there is a 25% chance of the child having the disease. A blood test and prenatal tests can check for the gene or the disease.

There is no cure. Medicines and good nutrition can help some symptoms. Some children need feeding tubes.

NIH: National Institute of Neurological Disorders and Stroke


Tay-Sachs Disease
Brain and Nerves
Genetics/Birth Defects
Tay-Sachs disease is a rare, inherited disease. It is a type of lipid metabolism disorder. It causes too much of a fatty substance to build up in the brain. ...
Metabolic Disorders
National Library of Medicine
Mucolipidoses

Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive system break the food parts down into sugars and acids, your body's fuel. Your body can use this fuel right away, or it can store the energy in your body tissues, such as your liver, muscles, and body fat.

A metabolic disorder occurs when abnormal chemical reactions in your body disrupt this process. When this happens, you might have too much of some substances or too little of other ones that you need to stay healthy. There are different groups of disorders. Some affect the breakdown of amino acids, carbohydrates, or lipids. Another group, mitochondrial diseases, affects the parts of the cells that produce the energy.

You can develop a metabolic disorder when some organs, such as your liver or pancreas, become diseased or do not function normally. Diabetes is an example.


Metabolic Diseases
Genetics/Birth Defects
Metabolic Problems
Metabolism is the process your body uses to get or make energy from the food you eat. Food is made up of proteins, carbohydrates, and fats. Chemicals in your digestive ...
Klinefelter's Syndrome
National Library of Medicine
XXY male

Klinefelter syndrome (KS) is a condition that occurs in men who have an extra X chromosome. The syndrome can affect different stages of physical, language, and social development.

The most common symptom is infertility. Boys may be taller than other boys their age, with more fat around the belly. After puberty, KS boys may have

  • Smaller testes and penis
  • Breast growth
  • Less facial and body hair
  • Reduced muscle tone
  • Narrower shoulders and wider hips
  • Weaker bones
  • Decreased sexual interest
  • Lower energy

KS males may have learning or language problems. They may be quiet and shy and have trouble fitting in.

A genetic test can diagnose KS. There is no cure, but treatments are available. It is important to start treatment as early as possible. With treatment, most boys grow up to have normal lives.

Treatments include testosterone replacement therapy and breast reduction surgery. If needed, physical, speech, language, and occupational therapy may also help.

NIH: National Institute of Child Health and Human Development


Klinefelter Syndrome
Genetics/Birth Defects
Men
Klinefelter syndrome (KS) is a condition that occurs in men who have an extra X chromosome. The syndrome can affect different stages of physical, language, and social ...