May 11, 2022

Empowering Families through Carrier Screening: A Guide to Genetic Testing for Inherited Diseases

Eli Sward, PhD; Eldar Dedic

Originally Posted by:Geneyx

Empowering Families through Carrier Screening: A Guide to Genetic Testing for Inherited Diseases Genetic carrier screening is a type of genetic test that identifies carriers of specific genetic disorders who may not exhibit symptoms of the disease but have the potential to pass it on to their children. Carrier screening is typically done before or during pregnancy and is used to determine the likelihood that a couple will have a child with a genetic disorder. Carrier screening is a form of preventive medicine that can help individuals and families make informed decisions about family planning and reproductive health.

The Importance of Genetic Screening

1. Identify carriers of genetic disorders: Genetic carrier screening can identify individuals who carry causative genetic variants for specific disorders, even if they do not have symptoms. This information can assess the risk of having a child with the disorder and inform decisions about family planning.

2. Prevent genetic disorders: If both partners are carriers of a genetic disorder, there is a 25% chance that their child will inherit the disorder. With carrier screening, couples can learn about their risk and take steps to prevent the condition from being passed on to their children. This may include using assisted reproductive technologies like in vitro fertilization (IVF) and preimplantation genetic testing (PGT).

3. Prepare for a child with a genetic disorder: If a couple knows that they are at increased risk of having a child with a genetic disorder, they can prepare for the possibility of having a child with causative variant in homozygous or compound heterozygous state. This may include seeking medical care from specialists who can provide appropriate treatment and support, connecting with support groups, and making lifestyle changes to accommodate the needs of a child with a genetic disorder.

4. Inform family members: Genetic carrier screening can also provide information that may be useful for other family members who may be at increased risk of being carriers or having a child with a genetic disorder. This information can help inform their own reproductive decisions and medical care. Inherited genetic disorders are conditions caused by abnormalities in an individual’s genetic makeup that are passed down from parents to children. These disorders can be caused by a causative variant(s) in a single gene or by changes in the structure or number of chromosomes.
Inherited genetic disorders can affect any part of the body and can vary widely in severity. They may be inherited in an autosomal dominant, autosomal recessive, or X-linked manner. Some inherited genetic disorders can be identified through carrier screening, which can help individuals and couples make informed decisions about family planning and reproductive health.

Carrier Screening – What you need to know

Types of Inherited Genetic Disorders

Autosomal recessive disorders – Occur when an individual inherits two copies of a mutated gene, one from each parent. Typically, the parents of an individual with an autosomal recessive disorder are carriers of the mutated gene, meaning they each have one copy of the mutated gene but do not show any symptoms of the disorder.

Autosomal dominant disorders – A type of genetic disorder that occurs when an individual inherits one copy of a mutated gene from either parent and the disorder is usually present in at least one of the parents.

X-linked disorders – Occur when a mutated gene is located on the X chromosome, and males are more commonly affected because they have only one X chromosome.

Multifactorial disorders – A genetic disorder resulting from a combination of genetic and environmental factors, and the risk of developing these disorders can be influenced by factors such as lifestyle, diet, and exposure to toxins.

Genetic Testing Methods Used for Carrier Screening

There are several genetic testing methods used for carrier screening. Each method has positive
and/or negative implications:

1. DNA sequencing: This method involves analyzing an individual’s DNA to identify specific
gene mutations associated with genetic disorders.

2. Targeted mutation analysis: Tests for known mutations in specific genes associated with genetic disorders, often used when a specific mutation is already known to be present in a family.

3. Next-generation sequencing (NGS): This high-throughput sequencing technique can analyze multiple genes or the entire genome for mutations associated with genetic disorders. NGS allows for the analysis of multiple genes or genome, making it a powerful
tool for genetic screening and diagnosis.

The future of NGS and long read sequencing holds promise for improved accuracy, faster analysis times, and the ability to analyze DNA in real time, which could significantly impact personalized medicine and disease diagnosis and treatment.

4. Microarray analysis: This method involves analyzing an individual’s DNA for changes in the number of copies of specific genes, which can be associated with certain genetic disorders.

5. Biochemical testing: This method involves measuring the level of a specific protein or metabolite in an individual’s blood or other bodily fluids to detect the presence of a genetic disorder.

Ethical Issues with Carrier Screening

Genetic carrier screening raises several ethical considerations, including issues of informed consent, privacy, and discrimination. Individuals who undergo carrier screening should be fully informed about the implications of the test results, including the potential emotional and psychological impact and the risk of passing on a genetic disorder to their children. Ethical considerations also extend to the use of carrier screening for population based screening programs, as it raises questions about the balance between individual autonomy and the public interest in preventing genetic disorders. Overall, ethical considerations and genetic counseling are crucial components of carrier screening to ensure that individuals and couples are fully informed about the implications of their test results and can make informed decisions about their reproductive health.

The Future and Advances in Carrier Screening Technology

Carrier screening technology has rapidly advanced in recent years, and several future directions promise to improve its accuracy and accessibility. One promising approach is using next-generation sequencing (NGS) technologies, such as those
offered by Geneyx Analysis. Geneyx analysis uses NGS and allows for the analysis of large amounts of genetic information in a single test, making it possible to screen for many genetic disorders simultaneously. This approach can significantly reduce the cost and time required for carrier screening and can increase the accuracy and validity of results.

Using FASTQ on the Geneyx platform creates fast testing methods that can provide results within a few hours or even minutes. Rapid testing could be beneficial in urgent clinical situations, such as when a newborn is suspected of having a genetic disorder. Machine learning algorithms and artificial intelligence (AI) to analyze and interpret carrier screening results are essential. Geneyx helps to identify complex patterns and relationships in genetic data and can improve the accuracy and validity of carrier screening results. Finally, advances in genome editing technologies, such as CRISPR/Cas9, hold promise for the prevention or treatment of genetic disorders. By editing or correcting genetic mutations, it may be possible to prevent the transmission of genetic disorders from one generation to the next. Overall, the future of carrier screening technology is bright, and ongoing research and development will likely lead to further improvements in accuracy, validity, and accessibility. With technologies like NGS and AI, carrier screening can provide valuable information for individuals and couples to make informed decisions about family planning and reproductive
health.

References:
Carrier screening for inherited genetic disorders | BabyCenter
Antonarakis, S.E. Carrier screening for recessive disorders. Nat Rev Genet 20, 549–561 (2019).
https://doi.org/10.1038/s41576-019-0134-2 

Carrier screening for recessive disorders | Nature

Reviews Genetics
RACGP – Three-condition genetic carrier screening to become free – Three-condition genetic
carrier screening to become free
Societal implications of expanded universal carrier screening: a scoping review
Societal implications of expanded universal carrier screening: a scoping review | European
Journal of Human Genetics (nature.com)
• Lieke M. van den Heuvel,
• Nina van den Berg,
• A. Cecile J. W. Janssens,
• Erwin Birnie,
• Lidewij Henneman,
• Wybo J. Dondorp,
• Mirjam Plantinga &
• Irene M. van Langen
European Journal of Human Genetics volume 31, pages55–72 (2023)
Geneyx Genomex – NGS Data Analysis | Clinical Genome Research | Geneyx

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