Genetic Test

"You should know what you have been planned."
​What is Genetic Test? Do my child need to be tested?

 

Linking Child Genetic Test is taken as medical test that identifies the heritage sequence of child.  It is to confirm, study the chance of or rule out a known genetic sequences or patterns that may contribute the higher risk of genetic disorder.  Linking Child Genetic Test is "chromosomal genetic test" analyzing whole chromosomes of your child DNA, which is among the best and most comprehensive tests in the world.  

 

Genetic testing is voluntary.  If your child is behaving at his very early age differently from other children, you are advised to consultant doctor who can advise the correct usage of Genetic Test to help your children.  

​When shall my child be tested?

Genetic testing can provide information about a person's chromosomes and genetic messages.  Normally you can consider the following types of tests:

 

Newborn screening

Newborn screening is used in the pregnancy stage of in the early stage after birth to identify genetic disorders.  This is particular necessary for genetic issues that should be effectively treated early in life.  There are many tests for genetic disorders.  The popular infants test are the test of genetic disorder causing intellectual disability if left untreated, named phenylketonuria and thyroid gland disorder, named congenital hypothyroidism.  Millions of babies are tested each year in the United States. 

Diagnostic testing

Diagnostic testing is used to rule out or provide empirical evidence of a specific genetic or chromosomal condition. In many cases, genetic testing is used to provide more medical confirmation of a diagnosis which is based solely on children' behavioral patterns, clinical observation and suspected symptoms.  Diagnostic testing can be used at any time when we want to doubt check the accuracy of the earlier diagnosis with a genetic points of view.  The results of a diagnostic test can provide genetic information which can share insight about the treatment, intervention and management of the disorder.

Carrier testing

Carrier testing is used to identify people who may carry a hidden features of a genetic disorder.  People with known or unknown family history of genetic disorder will normally taking Carrier Test.  If both parents are tested, the test can provide information about a couple's risk of having a child with a genetic condition.

Prenatal testing

Prenatal testing is used to detect fetus's genes or chromosomes before birth.  Mother in their pregnancy stage may take this test for the risk of the baby's genetic or chromosomal disorder.  In some cases, prenatal testing can identify the risk of a couple in having a genetically defected fetus.  However, it cannot identify all possible inherited disorders and birth defects.  It is best to consult your doctor for more information.

Preimplantation testing

Preimplantation testing, also called preimplantation genetic diagnosis (PGD), is used to reduce the risk of having a genetic or chromosomal disorder child.  It is to detect genetic changes in embryos in the process of in-vitro fertilization. In-vitro fertilization is a technique of outside body fertilization.  To perform preimplantation testing, only the healthy embryos will be allowed to initiate a pregnancy .  

Predictive and presymptomatic testing

Predictive tests are done by people who are seen normal, but having a family member with a genetic disorder.  It can identify genes or chromosomes changes that increase a person's risk of developing disorders.   Family members die of certain types of cancer would like to preform Predictive tests.  Predictive testing can determine whether a person will develop a genetic disorder, such as hereditary hemochromatosis, before any signs or symptoms appear.  People knowing the test result can make timely decision about their risk of developing a specific disorder and make decisions on medical care and living style.  

How can consumers be sure a genetic test is valid and useful?

Before undergoing genetic testing, it is important to be sure that the test is valid and useful. A genetic test is valid if it provides an accurate result. Two main measures of accuracy apply to genetic tests: analytical validity and clinical validity. Another measure of the quality of a genetic test is its usefulness, or clinical utility.

  • Analytical validity refers to how well the test predicts the presence or absence of a particular gene or genetic change. In other words, can the test accurately detect whether a specific genetic variant is present or absent?

  • Clinical validity refers to how well the genetic variant being analyzed is related to the presence, absence, or risk of a specific disease.

  • Clinical utility refers to whether the test can provide information about diagnosis, treatment, management, or prevention of a disease that will be helpful to a consumer.

 

All laboratories that perform health-related testing, including genetic testing, are subject to federal regulatory standards called the Clinical Laboratory Improvement Amendments (CLIA) or even stricter state requirements. CLIA standards cover how tests are performed, the qualifications of laboratory personnel, and quality control and testing procedures for each laboratory. By controlling the quality of laboratory practices, CLIA standards are designed to ensure the analytical validity of genetic tests.

 

CLIA standards do not address the clinical validity or clinical utility of genetic tests. The Food and Drug Administration (FDA) requires information about clinical validity for some genetic tests. Additionally, the state of New York requires information on clinical validity for all laboratory tests performed for people living in that state. Consumers, health providers, and health insurance companies are often the ones who determine the clinical utility of a genetic test.

 

It can be difficult to determine the quality of a genetic test sold directly to the public. Some providers of direct-to-consumer genetic tests are not CLIA-certified, so it can be difficult to tell whether their tests are valid. If providers of direct-to-consumer genetic tests offer easy-to-understand information about the scientific basis of their tests, it can help consumers make more informed decisions. It may also be helpful to discuss any concerns with a health professional before ordering a direct-to-consumer genetic test.

What does a positive result mean of my genetic test?

The results of genetic tests are not always an yes/no report, when interpreting test results, it is recommended to consult your doctor or related professionals.  It is necessary to consider a your medical and family history, in relating to the your genetic test.

 

A positive test result means that the laboratory found a targeted pattern of interest.  Depending on the type of the test, this result may suggest a person is carrying a similar pattern of people having a disease or genetic disease.  This will assist the doctor or professionals the confirmation of a diagnosis, indicating that a person is a carrier of a particular genetic mutation.  It is suggesting a risk factor of developing such a disease (such as cancer or ADHD) in the future.   It also suggest that blood relatives of the person may be a genetic carry also.  He/She may need to do a predictive or presymptomatic genetic test as well.  

In some cases, a test result might give neither positive nor negative information. This type of result is called inconclusive, or ambiguous. Inconclusive test results sometimes occur because the DNA's variations do not affect health, but an inconclusive result cannot confirm or rule out a targeted diagnosis.

What are whole exome sequencing and whole genome sequencing?

DNA sequencing test is to identify the order of DNA building blocks of a person for genetic disorders.  There are two common next-generation sequencing methods.  They are whole exome sequencing (WES) and whole genome sequencing (WGS), relying on new technologies that allow rapid sequencing of large amounts of DNA. These approaches are known as next-generation sequencing (or next-gen sequencing).

With next-generation sequencing, it is now feasible to sequence all proteins-making instructions giving DNA (exons).  Exons are thought to make up 1% of a person's genome.   Together, all the exons in a genome are known as the exome, and the method of sequencing them is known as whole exome sequencing (WES).  

 

However, researchers have found that DNA variations outside the exons can affect gene activity and protein production and lead to genetic disorders.  Therefor variations that whole exome sequencing would miss the detection of some genetic disorders.  Therefore there is a more comprehensive method, called whole genome sequencing (WGS).  It can determine the order of all the nucleotides in an individual's DNA and can determine variations in any part of the genome.  In addition to being used in the clinic practices, whole exome and whole genome sequencing are valuable methods for our researchers as well. Continued study of exome and genome sequences can help determine whether new genetic variations are associated with health conditions, which will aid disease diagnosis in the future.  It is necessary for people to revisit their DNA with the latest genetic disorders findings.   An unidentified variant of a genetic disorder that has not yet been diagnosed is called incidental or secondary findings.

© 2019 by Linking Child Genetic Health Service Ltd.

Contact us:

Tel: +852 8200 1121

Email: info@linkinghealth.com