Postnatal genetic tests help physicians diagnose congenital anomalies, diseases, and developmental delays in children.
DNA molecules are packaged into thread-like structures called chromosomes. Gene mutations can occur to the DNA sequences, chromosomal structures, or the number of chromosomes (aneuploidy). Genetic aberrations play an essential role in many diseases and congenital anomalies, including developmental delay, intellectual disabilities, and autism spectrum disorders.
With advances in human genetic research and analysis technologies, various types of causative genetic aberrations associated with disorders can be detected thus providing valuable information to aid the healthcare team and parents in the child’s care management.
Types of postnatal genetic tests
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 become 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.
Benefits of postnatal genetic testing
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. 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 to diagnosis 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.