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
What are 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. 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. Others, like heart disease, are found using special tests. Birth defects can range from mild to severe. How a birth defect affects a child's life depends mostly on which organ or body part is involved and how severe the defect is.

What causes birth defects?

For some birth defects, researchers know the cause. But for many birth defects, the exact cause is unknown. Researchers think that most birth defects are caused by a complex mix of factors, which can include

  • Genetics. One or more genes might have a change or mutation that prevents them from working properly. For example, this happens in Fragile X syndrome. With some defects, a gene or part of the gene might be missing.
  • Chromosomal problems. In some cases, a chromosome or part of a chromosome might be missing. This is what happens in Turner syndrome. In other cases, such as with Down syndrome, the child has an extra chromosome.
  • Exposures to medicines, chemicals, or other toxic substances. For example, alcohol misuse can cause fetal alcohol spectrum disorders.
  • Infections during pregnancy. For example, infection with Zika virus during pregnancy can cause a serious defect in the brain.
  • Lack of certain nutrients. Not getting enough folic acid before and during pregnancy is a key factor in causing neural tube defects.
Who is at risk of having a baby with birth defects?

Certain factors may might increase the chances of having a baby with a birth defect, such as

  • Smoking, drinking alcohol, or taking certain "street" drugs during pregnancy
  • Having certain medical conditions, such as obesity or uncontrolled diabetes, before and during pregnancy
  • Taking certain medicines
  • Having someone in your family with a birth defect. To learn more about your risk of having a baby with a birth defect, you can talk with a genetic counselor,
  • Being an older mother, typically over the age of 34 years
How are birth defects diagnosed?

Health care providers can diagnose some birth defects during pregnancy, using prenatal testing. That's why it important to get regular prenatal care.

Other birth defects may not be found until after the baby is born. Providers may find them through newborn screening. Some defects, such as club foot, are obvious right away. Other times, the health care provider may not discover a defect until later in life, when the child has symptoms.

What are the treatments for birth defects?

Children with birth defects often need special care and treatments. Because the symptoms and problems caused by birth defects vary, the treatments also vary. Possible treatments may include surgery, medicines, assistive devices, physical therapy, and speech therapy.

Often, children with birth defects need a variety of services and may need to see several specialists. The primary health care provider can coordinate the special care that the child needs.

Can birth defects be prevented?

Not all birth defects can be prevented. But there are things you can do before and during pregnancy to increase your chance of having a healthy baby:

  • Start prenatal care as soon as you think you might be pregnant, and see your health care provider regularly during pregnancy
  • Get 400 micrograms (mcg) of folic acid every day. If possible, you should start taking it at least one month before you get pregnant.
  • Don't drink alcohol, smoke, or use "street" drugs
  • Talk to your health care provider about any medicines you are taking or thinking about taking. This includes prescription and over-the-counter medicines, as well as dietary or herbal supplements.
  • Learn how to prevent infections during pregnancy
  • If you have any medical conditions, try to get them under control before you get pregnant

Centers for Disease Control and Prevention


Congenital Abnormalities
Genetics/Birth Defects
What are 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 ...
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 medical 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 ...
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 ...
Neural Tube Defects
National Library of Medicine
Anencephaly

Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the first month of pregnancy, often before a woman even knows that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In spina bifida, the fetal spinal column doesn't close completely. There is usually nerve damage that causes at least some paralysis of the legs. In anencephaly, most of the brain and skull do not develop. Babies with anencephaly are usually either stillborn or die shortly after birth. Another type of defect, Chiari malformation, causes the brain tissue to extend into the spinal canal.

The exact causes of neural tube defects aren't known. You're at greater risk of having an infant with a neural tube defect if you

  • Have obesity
  • Have poorly controlled diabetes
  • Take certain antiseizure medicines

Getting enough folic acid, a type of B vitamin, before and during pregnancy prevents most neural tube defects.

Neural tube defects are usually diagnosed before the infant is born, through lab or imaging tests. There is no cure for neural tube defects. The nerve damage and loss of function that are present at birth are usually permanent. However, a variety of treatments can sometimes prevent further damage and help with complications.

NIH: National Institute of Child Health and Human Development


Neural Tube Defects
Brain and Nerves
Genetics/Birth Defects
Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the first month of pregnancy, often before a woman even knows that ...