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Down Syndrome Glossary

Confused by the terminology? Use this glossary to get the definitions of commonly used terms and phrases relating to Down syndrome.

What is Duodenal Atresia?
Duodenal atresia, is a birth defect of the digestive tract, that occurs in approximately 5-7% of infants with Down syndrome.

What Is Alpha-fetoprotein or AFP
Alpha fetoprotein or AFP is a protein produced during pregnancy that is used to screen for Down syndrome and neural tube defects such as anencephaly or spina bifida.

Choroid Plexus Cysts and Down Syndrome
Choroid plexus cysts are a common finding on second trimester prenatal ultrasound. Most often, fetuses with choroid plexus cysts are perfectly healthy but there is a small association between choroid plexus cysts and chromosome problems such as Down syndrome.

Prenatal Ultrasound - What Is an Prentatal Ultrasound or sonogram
Prenatal ultrasound, also called a sonogram, is a technique that allows healthcare providers to see or visualize an unborn baby. There are many reasons to have a prenatal ultrasound which is also sometimes called a sonogram.

Trisomy 13
Trisomy 13 is a relatively rare chromosome abnormality that occurs in about 1 in 5,000 liveborn babies and is caused by the presence of an extra number 13 chromosome.

Neural Tube Birth Defects
Spina bifida is a common birth defect affecting the spinal cord that occurs in about 1 in 1000 pregnancies.

Trisomy 18 or Edwards Syndrome
Trisomy 18 is a relatively rare chromosome abnormality that occurs in about 1 in 6000 babies caused by the presence of an extra number 18 chromosome.

Neural Tube Birth Defects
Anencephaly is a relatively common lethal birth defect cause by a failure of neural tube development and resulting in resulting in the absence of a major portion of the brain, skull, and scalp.

Screening Test - What is a Screening Test?
Screening tests are commonly used in pregnancy to determine who is at increased risk to have a baby with a chromosome abnormality such as link url=http://downsyndrome.about.com/od/downsyndromebasics/a/downsynessen.htm]Down Syndrome[/link}. Read here for more information about screening tests.

Amniocentesis
An amniocentesis is a test performed during pregnancy that can detect Down syndrome and other chromosome disorders.

Chorionic Villi Sampling (CVS)
Chorionic villi sampling (known as CVS for short) is a test performed during early pregnancy to detect Down syndrome and other chromosome disorders.

Prenatal Testing - What is Prenatal Testing?
Prenatal tests are tests done during pregnancy to detect or to screen for genetic disorders or other birth defects such as Down syndrome.

Robertsonian Translocation - What is a Robertsonian Translocation?
Definition of a Robertsonian translocation and how they can cause Down syndrome.

Translocation Down Syndrome - What is Translocation Down Syndrome?
Translocation Down syndrome is responsible for 4 to 5% of the diagnosed cases of Down syndrome. While the basic problem is the same - three copies of the number 21 chromosome, the mechanism leading this problem is different than the mechanism leading to trisomy 21, and the recurrence risk can be very different. Read on to learn more.

Reciprocal Translocation
Definition of a reciprocal chromosome translocation and how they can cause Down syndrome.

Neurologist
neurologist definition

Atlantoaxial Instability
Atlantoaxial Instability, often referred to as AAI, is a condition affecting the top of the spinal cord. About 15% of people with Down sydnrome will have AAI although most will never have symptoms of this disorder. Read here to learn more about this condition, how it is diagnosed, it's symptoms and treatments.

Neurosurgeon
Definition of a neurosurgeon

Cytogenetics
Definition of cytogenetics

Hypotonia
Definition of hypotonia

Syndrome
The definition of a syndrome.

Mosaic Down Syndrome
Mosaic Down syndrome definition

Translocation
Definition of a translocation

Definition of Mosaic Down Syndrome
Definition Of Mosaic Down Syndrome

Definition of a Karyotype
The definition of karyotype.

Chromosome
Definition of a chromosome.

Trisomy
Definition of trisomy

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