child kissing pregnant belly

What are prenatal and postnatal genetic testing?

Prenatal genetic testing performed during pregnancy helps physicians detect congenital anomalies or genetic disorders in the fetus. If a screening test, such as ultrasound, is found to be abnormal or if there is a family history of a genetic disorder prenatal testing may be recommended.

Postnatal genetic testing helps physicians diagnose congenital anomalies, diseases, and developmental delays in children.

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Genetic testing focuses on DNA molecules that are packaged into thread-like structures called chromosomes. Gene mutations occur due to changes to the DNA sequence, chromosomal structure, or number of chromosomes. Genetic aberrations play an essential role in many genetic disorders and can be inherited from parents or occur spontaneously during embryonic development.

With advances in human genetic research and analysis technologies, various types of causative genetic aberrations associated with disorders can be detected prenatal and postnatal thus providing valuable information to aid parents, physicians, and genetic counselors in making the best decisions before and after birth.

Dr. Mary Norton provides an overview of chromosomal microarrays (CMA).

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amnio testing

Prenatal genetic tests can be performed using DNA extracted from amniocytes (amniocentesis), chorionic villus sampling (CVS), or circulating fetal DNA (cfDNA). Genetic testing of cfDNA, unlike amniocentesis and CVS, is non-invasive since it is present in the mother’s blood.

Karyotyping, the traditional prenatal genetic test, is a low-resolution method that examines a picture of stained chromosomes. Because of its low resolution, certain genetic disorders, such as those with tiny mutations, can be missed by karyotyping.

Chromosomal Microarray Analysis (CMA) is a microarray-based analysis that can analyze DNA of known genes from the entire human genome in one test. It is a high-resolution test useful in analyzing the entire genome or a subset of the genome for the detection of aberrations in multiple genes, changes in chromosomal structure, and chromosomal aneuploidy.

DNA sequencing of cfDNA, which is also referred to as non-invasive prenatal testing or NIPT, reduces the need for invasive procedures and can be beneficial for women diagnosed with high-risk pregnancies. Most NIPT is a screening test, so positive results must be confirmed by another diagnostic methodology, according to American College of Obstetricians and Gynecologists (ACOG) guideline #163

ultrasound

Prenatal testing provides information on the health of the mother and the baby during pregnancy and the baby’s risk of developing genetic disorders. Having this valuable information enables parents and their physicians to proactively manage both the mother’s and baby’s health during pregnancy and after birth.

blood sample

Typical postnatal genetic tests are performed by analyzing a blood sample from the child and the parents. DNA from the blood is extracted, amplified, processed, and analyzed using advanced software.

Chromosomal Microarray Analysis (CMA) is a microarray-based analysis that can analyze DNA of known genes from the entire human genome in one test. It is considered the first-line test for multiple congenital anomalies, developmental delays, intellectual disabilities, and autism spectrum disorders. It is a high-resolution test useful in analyzing the entire genome or a subset of the genome for the detection of aberrations in multiple genes, changes in chromosomal structure, and chromosomal aneuploidy.

As next-generation sequencing becomes more accessible for routine clinical use, whole genome sequencing and whole exome sequencing are becoming more prevalent for postnatal genetic testing. Whole genome sequencing (WGS) analyzes all the DNA sequences for an individual looking for known causative variants. Whole exome sequencing (WES) analyzes only the DNA sequences for all the genes coding for proteins (representing about 1% of one’s entire genome).

Depending on the patient's case, clinicians will use the proper tests to help with finding and confirming a diagnosis.

baby feet

When parents observe developmental delays or disease symptoms in their child, having test after test done without producing a definite diagnosis could be very frustrating and increase anxiety. Having a diagnosis often brings relief and a sense of control for the parents. Also, for many congenital abnormalities and other genetic disorders, having an early diagnosis can provide physicians and parents with valuable information for early intervention, treatment, and proactive management of a child’s health and a family’s lifestyle. 

With the advanced genetic testing technologies available today, not only is it attainable to obtain more precise genetic information with confidence, but also the journey through the diagnostic odyssey is shortened, which for some could be life-saving.

An additional benefit of having a child’s genetic information is the help it may provide parents with future family planning. If the genetic test shows a child has causative genetic aberrations, which could be inherited or occurred de novo during embryo development, it is highly recommended that the parents consider preconception carrier screening to determine their carrier status when they plan to grow their family.

amnio testing

Prenatal genetic tests can be performed using DNA extracted from amniocytes (amniocentesis), chorionic villus sampling (CVS), or circulating fetal DNA (cfDNA). Genetic testing of cfDNA, unlike amniocentesis and CVS, is non-invasive since it is present in the mother’s blood.

Karyotyping, the traditional prenatal genetic test, is a low-resolution method that examines a picture of stained chromosomes. Because of its low resolution, certain genetic disorders, such as those with tiny mutations, can be missed by karyotyping.

Chromosomal Microarray Analysis (CMA) is a microarray-based analysis that can analyze DNA of known genes from the entire human genome in one test. It is a high-resolution test useful in analyzing the entire genome or a subset of the genome for the detection of aberrations in multiple genes, changes in chromosomal structure, and chromosomal aneuploidy.

DNA sequencing of cfDNA, which is also referred to as non-invasive prenatal testing or NIPT, reduces the need for invasive procedures and can be beneficial for women diagnosed with high-risk pregnancies. Most NIPT is a screening test, so positive results must be confirmed by another diagnostic methodology, according to American College of Obstetricians and Gynecologists (ACOG) guideline #163

ultrasound

Prenatal testing provides information on the health of the mother and the baby during pregnancy and the baby’s risk of developing genetic disorders. Having this valuable information enables parents and their physicians to proactively manage both the mother’s and baby’s health during pregnancy and after birth.

blood sample

Typical postnatal genetic tests are performed by analyzing a blood sample from the child and the parents. DNA from the blood is extracted, amplified, processed, and analyzed using advanced software.

Chromosomal Microarray Analysis (CMA) is a microarray-based analysis that can analyze DNA of known genes from the entire human genome in one test. It is considered the first-line test for multiple congenital anomalies, developmental delays, intellectual disabilities, and autism spectrum disorders. It is a high-resolution test useful in analyzing the entire genome or a subset of the genome for the detection of aberrations in multiple genes, changes in chromosomal structure, and chromosomal aneuploidy.

As next-generation sequencing becomes more accessible for routine clinical use, whole genome sequencing and whole exome sequencing are becoming more prevalent for postnatal genetic testing. Whole genome sequencing (WGS) analyzes all the DNA sequences for an individual looking for known causative variants. Whole exome sequencing (WES) analyzes only the DNA sequences for all the genes coding for proteins (representing about 1% of one’s entire genome).

Depending on the patient's case, clinicians will use the proper tests to help with finding and confirming a diagnosis.

baby feet

When parents observe developmental delays or disease symptoms in their child, having test after test done without producing a definite diagnosis could be very frustrating and increase anxiety. Having a diagnosis often brings relief and a sense of control for the parents. Also, for many congenital abnormalities and other genetic disorders, having an early diagnosis can provide physicians and parents with valuable information for early intervention, treatment, and proactive management of a child’s health and a family’s lifestyle. 

With the advanced genetic testing technologies available today, not only is it attainable to obtain more precise genetic information with confidence, but also the journey through the diagnostic odyssey is shortened, which for some could be life-saving.

An additional benefit of having a child’s genetic information is the help it may provide parents with future family planning. If the genetic test shows a child has causative genetic aberrations, which could be inherited or occurred de novo during embryo development, it is highly recommended that the parents consider preconception carrier screening to determine their carrier status when they plan to grow their family.


CACdb

Are you trying to learn more about how to deal with rare and challenging prenatal cases? The Cytogenomics Array Group CNV Database (CAGdb) may be the answer.

Find out more