3. • Prenatal diagnosis and prenatal screening are aspects of
prenatal care that focus on detecting anatomic and
physiologic problems with the zygote, embryo, or fetus
as early as possible, either before gestation even starts
(as in preimplantation genetic diagnosis) or as early in
gestation as practicable.
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The medical tests is applied to detect problems such as
neural tube defects, chromosome abnormalities, and gene
mutations that would lead to genetic disorders and birth
defects, such as spina bifida,
Cleft Palate,
Sickle Cell Anemia,
Thalassemia,
Cystic Fibrosis,
Muscular Dystrophy etc
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Common testing procedures include
Amniocentesis,
Ultrasonography Including Nuchal Translucency
Ultrasound,
Serum Biomarker Testing, Or
Genetic Screening
6. Amniocentesis
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Amniocentesis (also referred to as amniotic fluid test or
AFT) is a medical procedure used in prenatal diagnosis
of chromosomal abnormalities and fetal infections and
also for sex determination
Here a small amount of amniotic fluid, which contains
fetal tissues, is sampled from the amniotic sac
surrounding a developing fetus, and then the fetal DNA is
examined for genetic abnormalities.
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The most common reason to have an "amnio" is to
determine whether a baby has certain genetic disorders
or a chromosomal abnormality, such as Down syndrome.
Amniocentesis is performed when a woman is between
14 and 16 weeks gestation.
8.
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Early in pregnancy, amniocentesis is used for diagnosis of
chromosomal and other fetal problems such as:
Down syndrome (trisomy 21)
Trisomy 13
Trisomy 18
Fragile X syndrome
Rare, inherited metabolic disorders
Neural tube defects (anencephaly and spina bifida) by
alpha-fetoprotein levels.
10. Medical ultrasound
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Medical ultrasound (also known as diagnostic
sonography or ultrasonography) is a diagnostic imaging
technique based on the application of ultrasound.
It is used to see internal body structures such as
tendons, muscles, joints, vessels and internal organs.
11. Nuchal scan
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A nuchal scan or nuchal translucency (NT) scan/procedure is
a sonographic prenatal screening scan (ultrasound) to detect
cardiovascular abnormalities in a fetus.
Since chromosomal abnormalities can result in impaired
cardiovasular development, a nuchal translucency scan is
used as a screening, rather than diagnostic, tool for conditions
such as Down syndrome.
12. Biomarker
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A biomarker, or biological marker, generally refers to a
measurable indicator (Eg. Enzyme, protein or DNA
sequence etc) of some biological state or condition.
In genetics, a biomarker (identified as genetic marker) is
a DNA sequence that causes disease or is associated
with susceptibility to disease.
13. Genetic screening
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Genetic testing can be used to determine a child's
parentage (genetic mother and father) or in general a
person's ancestry or biological relationship between
people.
In addition to studying chromosomes to the level of
individual genes, genetic testing in a broader sense
includes biochemical tests for the possible presence of
genetic diseases, or mutant forms of genes associated
with increased risk of developing genetic disorders.
14. • Genetic testing is "the analysis of chromosomes (DNA),
proteins, and certain metabolites in order to detect
heritable disease-related genotypes, mutations,
phenotypes, or karyotypes for clinical purposes.
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Diagnostic testing: Diagnostic testing is used to diagnose
or rule out a specific genetic or chromosomal condition.
For example, people with a family history of polycystic
kidney disease (PKD) who experience pain or tenderness
in their abdomen, blood in their urine, frequent urination,
pain in the sides, a urinary tract infection or kidney stones
may decide to have their genes tested and the result could
confirm the diagnosis of PKD.
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Prenatal diagnosis: Used to detect changes in a fetus's
genes or chromosomes before birth.
This type of testing is offered to couples with an
increased risk of having a baby with a genetic or
chromosomal disorder.
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In some cases, prenatal testing can lessen a couple's
uncertainty or help them decide whether to abort the
pregnancy.
However, It cannot identify all possible inherited
disorders and birth defects
