My Testing Options - Resources

Alpha-fetoprotein (AFP)
AFP is a protein produced during pregnancy that can be measured through a blood test once you’re at least 15 weeks pregnant. It can be used to determine the chance of having a baby affected with Down syndrome, trisomy 18 and open neural tube defects. See also Maternal Serum-Alpha-Fetoprotein (MSAFP) Screening.

Amniocentesis
Performed when you’re between 15 and 21 weeks pregnant, amniocentesis is a procedure to obtain amniotic fluid. The fluid can be tested for chromosomal disorders and open neural tube defects. It can also be used to test for certain genetic disorders such as cystic fibrosis and sickle cell disease, if your pregnancy is determined to be at increased risk for a genetic disorder. It can’t test for the 3-5% of birth defects that are everyone’s background risk.

The procedure involves withdrawing amniotic fluid (the fluid surrounding the developing baby). This fluid contains fetal cells that can be used for chromosome testing. The fluid also contains alpha-fetoprotein (AFP) that is used in testing for open neural tube defects.

Amniotic Fluid Alpha-fetoprotein Testing
An analysis of alpha-fetoprotein in the amniotic fluid to detect open neural tube defects.

Anencephaly
Anencephaly is a severe form of an open neural tube defect which results in the absence of much (or a major part) of the brain.

Ashkenazi Jewish
Individuals whose ancestors are of Eastern European Jewish descent. Their ethnicity can be traced back to countries such as Germany, Hungary, Poland, and Russia.

Autism
A disability usually characterized by the abnormal development of communication skills, social skills, and reasoning. The underlying cause of autism is not well understood and prenatal testing for all causes of autism is not available.

Autosomal Dominant Disease
Inherited disease for which one parent needs to carry a non-working copy of a gene in order to have an increased chance (50%) to have a baby with the disease. It affects males and females equally. Examples of autosomal dominant conditions include Marfan syndrome, Huntington disease, and neurofibromatosis.

Autosomal Recessive Disease
Inherited disease for which both parents need to carry a non-working copy of the same gene in order to have an increased chance (25%) to have a baby with the disease. It affects males and females equally. Examples of autosomal recessive conditions include cystic fibrosis, sickle cell disease, and Tay-Sachs disease.

Background Risk
For every 100 babies that are born, 3-5 will have a major birth defect. This 3-5% is known as the background risk.

Birth Defect
An abnormality that is present at birth (for example, Down syndrome or spina bifida or a heart defect). Birth defects can have many different causes. Not all birth defects can be detected by prenatal testing or ultrasound examination.

Bloom Syndrome
Bloom syndrome causes poor growth, poor immune system function, sun sensitivity, and a high rate of cancer. Individuals with Bloom syndrome usually die from cancer before age 30. Bloom syndrome does not affect intelligence.

Canavan Disease
Canavan disease is a disorder which causes brain and nervous system degeneration. Symptoms usually occur within the first few months of life and individuals with Canavan disease usually die in early childhood. There is currently no treatment.

Carrier
An individual who has a copy of a disease-causing gene but does not typically have the disease.

Carrier Testing
Carrier testing determines if a couple is at increased risk of having a baby with a specific inherited disease, such as Tay-Sachs disease or cystic fibrosis.

Chorionic Villi Sampling (CVS)
Performed when you’re between 10 and 12 weeks pregnant, chorionic villi sampling (CVS) is a procedure used to obtain a sample that can be tested for Down syndrome and other chromosomal disorders, as well as certain genetic disorders such as cystic fibrosis and sickle cell disease, if your pregnancy is determined to be at risk for a genetic disorder. CVS can’t test for the 3-5% of birth defects that are everyone’s background risk.

The procedure involves taking a small sample of tissue from the developing placenta.

Chromosome
Chromosomes are structures in the cells that contain the genes. A normal human cell has 46 chromosomes (23 pairs). A missing or extra chromosome causes many abnormalities in the way an unborn baby develops, and almost always leads to mental retardation and serious physical birth defects.

Chromosome Abnormality
A chromosome abnormality is an abnormality in the number or structure of chromosomes. For example, having three copies of a chromosome, instead of the normal two is called a trisomy. Also, any chromosome can have extra or missing pieces, which lead to serious birth defects.

Chromosome Testing
An analysis of the number and structure of chromosomes in a cell. A picture of the chromosomes from a cell arranged in the standard order is called a karyotype. View a karyotype.

Cleft Lip
A cleft lip is a congenital deformity characterized by failure of the lip tissue to grow normally, leading to a vertical gap or opening in the upper lip.

Congenital Disorder
A congenital disorder is a defect acquired during fetal development or present at birth. A congenital disorder is not necessarily hereditary.

Cystic Fibrosis (CF)
Cystic fibrosis is an autosomal recessive disease most common in individuals of Caucasian and Ashkenazi Jewish ancestry, but can also occur in other ethnic groups. Symptoms can vary from mild to severe, and include life-threatening lung infections, digestion problems, diarrhea, poor growth and infertility.

Diagnostic Test
Diagnostic tests indicate if your baby is affected or not affected with a specific birth defect or genetic disease, including Down syndrome. The accuracy of diagnostic testing depends on the test and on the birth defect or genetic disease tested. In contrast, see Screening Test.

Down Syndrome
Down syndrome, also known as trisomy 21, is a congenital disorder, caused by the presence of an extra #21 chromosome, in which the affected person has mild to moderate mental retardation, characteristic physical appearance, and often has physical problems, such as heart defects.

Estriol (also known as uE3)
This hormone is the main estrogen produced by the placenta during pregnancy and is measured in a blood test to determine the chance of having a baby affected with Down syndrome or trisomy 18.

Familial Dysautonomia
Familial dysautonomia is a progressive nervous system disorder that causes severe vomiting, decreased pain sensitivity, unstable blood pressure and temperature and frequent pneumonia. Individuals affected with familial dysautonomia often have normal intelligence, but may have learning disabilities. Symptom management improves quality of life, but only 50% of affected individuals will reach age 30.

Fanconi Anemia Group C
Fanconi anemia group C causes anemia, short stature and, often, abnormalities of the heart, kidneys and/or limbs. Some individuals have learning disabilities or mental retardation. The risk of early childhood cancer, especially leukemia, is increased.

Fragile X
Fragile X syndrome is the most common cause of inherited mental retardation, affecting approximately 1 in 4,000 males and 1 in 8,000 females. There may or may not be a family history of mental retardation.

Fragile X syndrome causes a range of symptoms. Early signs include delayed speech and language. Intellectual abilities vary from mild learning disabilities to severe mental retardation. Behavioral characteristics include autism, hyperactivity and poor eye contact. Physical features, such as a long face and large or prominent ears, are usually more noticeable in adults than in children, and in males more than females.

Gaucher Disease
Gaucher disease is a variable disease, caused by a particular enzyme deficiency. Children and adults with this condition may have anemia, enlarged liver and spleen, easy bruising, nosebleeds and fractures. The most common form of Gaucher disease, type 1, is treatable by enzyme replacement therapy. In the more severe form, which occurs much less frequently, the brain and nervous system are also involved; this form cannot be treated at this time.

Gene
A “blueprint” of hereditary information passed from parents to their children. An inherited disease (for example, cystic fibrosis) is caused by having non-working or absent genes

Genetic Disorder
A disease or condition caused by a defective or missing gene, a combination of genetic and environmental factors, or by a chromosome abnormality.

Glycogen Storage Disease Type 1a
Glycogen storage disease type 1a causes severe low blood sugar, enlarged liver, bleeding problems and delayed growth. Treatment requires a special diet often including tube feedings at night and/or during illness.

hCG
Human chorionic gonadotropin (hCG) is a hormone produced by the placenta during pregnancy, and is measured in a blood test to determine the chance of having a baby affected with Down syndrome or trisomy 18.

Infertility
The inability to become pregnant or carry a pregnancy to term after persistent attempts over a given period of time. Either men or women can be the cause of infertility.

Inherited Disease
An inherited disease is caused by mutations in a gene that are passed down from parents to their children. Tay-Sachs disease and cystic fibrosis are examples of inherited diseases.

Inhibin
Inhibin is a hormone measured in a blood test to determine the chance of having a baby affected with Down syndrome or trisomy 18.

In vitro fertilization
A technology in which an egg is fertilized in a laboratory and then transferred into the uterus.

Karyotype
A picture of the chromosomes from a cell arranged in the standard order.

Maple Syrup Urine Disease (MSUD)
Maple syrup urine disease (MSUD) causes certain amino acids to accumulate in the blood. The disease name refers to the characteristic smell of the urine. Without early diagnosis and treatment, classic MSUD leads to mental retardation, physical disabilities, seizures and death. Treatment, which consists of a strict, lifelong special diet, may help to control the accumulation of amino acids in the blood and may improve the symptoms.

Maternal Cells
Cells from the mother. These cells may be mixed in with the fetal sample and can interfere with the results.

Maternal Serum-Alpha-Fetoprotein (MSAFP) Screening
Performed when you’re between 15 and 20 weeks pregnant, maternal serum-alpha-fetoprotein (MSAFP) screening is a blood test to determine the chance of having a baby affected with an open neural tube defect.

Maternal Serum Screening Tests (see also Screening Test)
A group of tests that measure proteins and hormones in your blood during pregnancy to determine the chance of having a baby affected with Down syndrome, trisomy 18 or open neural tube defects. Examples include FirstScreen^®, SequentialScreen^SM and Afp4^®.

• Screen Positive = Screening test results showing an increased risk of having an affected baby. Your doctor will offer diagnostic testing to determine if your baby is affected with one of these birth defects.

• Screen Negative = Screening test results showing a low risk of having an affected baby. But, these screening tests don’t detect all affected pregnancies.

Mucolipidosis Type IV
Mucolipidosis type IV affects the brain and nervous system. Symptoms begin in the first year of life, and affected individuals have delayed developmental milestones, mental retardation and progressively worsening vision. There is currently no treatment.

Mutation
A change in a gene. In the context of medical genetics, mutations are disease-causing.

Niemann-Pick Disease Type A
Niemann-Pick disease type A causes poor growth, enlarged liver, and mental and physical deterioration. Individuals with Neimann-Pick disease type A usually die by age 4. There is currently no treatment.

Nuchal Translucency (NT)
A nuchal translucency is an ultrasound measurement of the fluid that collects behind the fetus’ neck between 10 and 13 weeks. More fluid indicates a greater risk of an abnormality.

Open Neural Tube Defects
The neural tube is a structure that develops into a baby’s spinal cord and brain. The tube is open early in the pregnancy and normally closes as the embryo develops. When the tube fails to close properly, it results in an opening. Severity varies depending upon the size and position of the opening.

An open neural tube defect causes a range of disabilities from paralyzed legs to incomplete brain development. Lack of closure above the neck results in anencephaly or encephalocele. Lack of closure below the neck results in spina bifida.

PAPP-A
Pregnancy-Associated Plasma Protein A is a protein that is measured in a blood test to determine the chance of having a baby affected with Down syndrome or trisomy 18.

Perinatologist
An obstetrician specializing in perinatology (the anatomy, physiology, diagnosis and treatment of disorders of the mother and the fetus or newborn baby).

Placenta
The sac-shaped organ that provides nutrients to the embryo or fetus during pregnancy.

Premature Ovarian Failure
Premature Ovarian Failure (POF) is the loss of function of the ovaries before age 40. One result of this condition is infertility. POF is not the same as menopause. See also Primary Ovarian Failure.

Primary Ovarian Failure
Primary amenorrhoea (menstruation cycles never starting) may be caused by developmental problems such as the congenital absence of the uterus, or failure of the ovary to receive or maintain egg cells. Also, delay in pubertal development will lead to primary amenorrhoea. See also Premature Ovarian Failure.

Recurrent Pregnancy Loss
Recurrent pregnancy loss is medically defined by 2 or more miscarriages at any stage during pregnancy.

Screening Test
Some screening tests are performed during pregnancy and others can be done before or during pregnancy. They can identify your chances of having a baby with disorders such as Down syndrome and cystic fibrosis. Maternal serum screening tests use a blood sample from the mother to identify pregnancies at risk for certain birth defects (in contrast, see also Diagnostic Test).

Sickle Cell Disease
Sickle cell disease is an autosomal recessive blood disorder that is more common in individuals of African descent, Caribbean descent, Middle Eastern countries, Mediterranean countries (including Turkey, Greece, and Italy), and India. Individuals with sickle cell disease usually have anemia, increased risk of infections and can be affected with “sickle cell crisis”, causing fever, pain, jaundice and other health complications.

Spina Bifida
Spina bifida is a congenital neural tube defect, resulting in an incomplete closure of the spinal column. Damage to the exposed spinal cord can cause neurological abnormalities, including paralysis.

Spinal Muscular Atrophy (SMA)
Spinal Muscular Atrophy (SMA) destroys the nerves responsible for controlling voluntary muscle movement, but does not affect intelligence. Muscles that control breathing, swallowing, head and neck control, walking, and crawling are the most severely affected. Symptoms most often appear before a baby is two years old, but can start before birth or not until adulthood.

Over 60% of individuals who are diagnosed with SMA are severely affected. There is currently no cure or treatment for SMA.

Tay-Sachs Disease
Tay-Sachs disease causes deterioration in both mental and physical abilities. Individuals with Tay-Sachs disease usually die by age 5. A less common form affects adults rather than children. At this time there is no treatment for Tay-Sachs disease.

Trisomy 13
Trisomy 13 is a congenital disorder caused by the presence of an extra #13 chromosome, occurring in about 1 out of 10,000 live births. Trisomy 13 is always fatal, with more than 80% of babies dying in the first month. The disorder is characterized by profound mental retardation, cardiac problems, and multiple deformities.

Trisomy 18
Trisomy 18 is a congenital disorder caused by the presence of an extra #18 chromosome, occurring in about 1 out of 3,000 to 1 out of 6,000 live births.

Trisomy 18 is always fatal, with 50% of babies dying within the first week and an additional 40% dying within the first year. The disorder is characterized by profound mental retardation, heart defects, and central nervous system defects.

Trisomy 21
Trisomy 21, also known as Down syndrome, is a congenital disorder, caused by the presence of an extra #21 chromosome, in which the affected person has mild to moderate mental retardation, characteristic physical appearance, and often has physical problems, such as heart defects.

uE3 (also known as Estriol)
This hormone is the main estrogen produced by the placenta during pregnancy. It is measured in a blood test to determine the chances of having a baby affected with Down syndrome or trisomy 18.

Ultrasound
An ultrasound (or sonogram) is a technology that uses sound waves to show images of the developing baby. The procedure may be done transvaginally or transabdominally. There are no known risks associated with ultrasound.

X-Linked Disease
Inherited disease for which the mother has to carry a non-working copy of a gene in order to have an increased chance (50%) to have a son with the disease. Examples of X-linked recessive conditions include Duchenne muscular dystrophy and hemophilia. Rarely, X-linked diseases may affect females as well as males, such as fragile X syndrome.