The Science of Carrier Screening | Phenome Longevity

What Is Carrier Screening?

Carrier screening is a genetic test that helps identify whether someone carries a change in their DNA that could be passed on to their children.

Every person carries genetic variations. Most of these are harmless, but some can affect how a gene functions. If both parents carry a change in the same gene, their child could inherit two altered copies and develop a genetic condition.

Carrier screening helps uncover these changes before they have an impact. It provides important knowledge that supports family planning and allows individuals to prepare for the future with clarity and confidence.

Did You Know?

Around 70 to 80% of severe inherited conditions can be identified and potentially prevented through modern carrier screening and genetic counselling.

How Our Genetic Code Is Built

The Code of Life: DNA Inside Every Cell

Inside every cell of your body is DNA, the molecule that holds all the instructions for how your body grows, develops, and functions. DNA is like a library made of millions of letters arranged in a specific order. When the sequence of letters changes, it can alter how the body interprets that information.

Chromosomes: How Your Genetic Blueprint Is Organized

DNA is packaged into chromosomes. Humans have 46 chromosomes in total, grouped into 23 pairs. One set comes from your mother and the other from your father. Twenty-two of these pairs are called autosomes and contain genes that determine most physical and biological traits. The last pair are the sex chromosomes. Females have two X chromosomes while males have one X and one Y chromosome.

Genes and Proteins: Turning Instructions Into Function

Each chromosome holds thousands of genes. A gene is a small segment of DNA that carries the instructions for making a specific protein. Proteins are essential for the body’s structure and function. They help build tissue, carry oxygen, regulate hormones, and control many vital processes.

When Genes Change: Variants and Mutations

When a gene changes, the protein it produces may not work as it should. Some changes are harmless and go unnoticed. Others may cause or contribute to disease. These changes are called variants or mutations.

A Closer Look at How Genetic Conditions Are Passed On

Carrier screening focuses on inherited conditions, meaning conditions that are passed from parents to their children through their genes.

In autosomal recessive inheritance, both parents must carry a variant in the same gene for a child to be affected. Each child then has a one in four chance of being affected, a one in two chance of being a carrier, and a one in four chance of being completely unaffected.

In autosomal dominant inheritance, one altered gene copy is enough to cause disease. If one parent has the variant, each child has a 50 percent chance of inheriting it.

X-linked conditions are slightly different. These are caused by changes in genes found on the X chromosome. Because males have one X and one Y chromosome, they are more likely to be affected if that gene is altered. Females have two X chromosomes, so even if one gene is affected, the other usually compensates, meaning they are typically carriers rather than affected individuals.

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Defining a Carrier

A carrier is a person who has one normal copy of a gene and one altered copy.

Carriers are healthy and show no symptoms because the unaffected gene copy still functions normally. However, they can pass their altered gene to their children.

If both parents are carriers of the same gene, their child may inherit two altered copies and develop that condition. This is why genetic conditions can sometimes appear in families with no previous history of disease. Carrier screening helps reveal this hidden information before pregnancy.

When to Have Carrier Screening

Carrier screening can be done at any time, but the best time is before pregnancy. Testing before conception allows enough time for couples to understand their results and explore all available options.

At Phenome Longevity, we do not recommend carrier screening after pregnancy has already begun. The purpose of the test is to prepare you, not to cause unnecessary stress later in pregnancy. Some clinics may offer carrier screening during the first ten weeks of gestation so that results are available early, when decisions are still manageable and supportive.

Why Carrier Screening Matters

Carrier screening is not about predicting illness. It is about learning how genetics work and using that information to make informed choices. It helps people understand that most genetic conditions do not appear because of family history but because of natural variations that can exist in anyone.

Understanding your carrier status provides reassurance and direction. It allows you to plan ahead, consider options, and take control of your family’s genetic health.

Examples of Genetic Conditions

There are thousands of genetic conditions, but a few are particularly well known and often included in carrier screening. Each condition affects the body in different ways, from how muscles work to how blood carries oxygen or how the nervous system develops. These includes:

Cystic Fibrosis

Sickle Cell Anaemia

Thalassaemia

Tay–Sachs Disease

Spinal Muscular Atrophy

Phenylketonuria

Duchenne Muscular Dystrophy

Fragile X Syndrome

This diagram shows how inherited conditions like cystic fibrosis are passed down when both parents carry one altered copy of the same gene. Each child has a 25% chance of being unaffected, a 50% chance of being a healthy carrier, and a 25% chance of inheriting the condition. This highlights why testing both parents is essential to understand the likelihood of passing on inherited conditions.

Carrier screening is most effective when both partners are tested. If only one partner is found to be a carrier, the other can then be tested for the same gene. If both partners carry changes in the same gene, there is an increased chance of having a child affected by that condition.

Testing both partners together provides a complete understanding of genetic risk. It allows couples to make decisions with full knowledge and ensures that healthcare professionals can offer appropriate guidance and counselling.

Risks and Limitations of Carrier Screening

Carrier screening is a powerful tool, but like any test, it has limits and emotional considerations.

Accuracy

Genetic testing is extremely reliable, but in rare cases a test might detect a change that is not truly present or may miss a change that does exist. These situations are uncommon but possible.

Scope

Carrier screening focuses on specific genes known to be linked to inherited conditions. It cannot detect every genetic variation that exists, nor can it identify brand new mutations that occur for the first time in an individual.

Emotional Impact

Learning about genetic risks can sometimes cause worry, particularly if both partners are found to be carriers. Understanding that being a carrier does not mean being ill is important. Genetic counselling can help interpret results in a calm and supportive way.

Timing

If carrier screening is done during pregnancy, it may lead to difficult emotions if concerning results arrive later in gestation. This is why it is generally recommended before conception.

Ethical Consideration

Discovering genetic information can influence family planning choices. These decisions are deeply personal, and thoughtful discussion with a healthcare professional is often helpful.

Practical Aspect

Genetic testing and any necessary follow-up tests can involve costs. For most people, however, the knowledge gained is considered a valuable investment in understanding and preparing for their family’s health.

How We Test

We use the most advanced technology in human history, Whole Genome Sequencing.

Through Whole Genome Sequencing, we analyse every part of your DNA to reveal meaningful insights about how your body functions, adapts, and inherits traits. This approach allows for a deeper, science-based understanding of your health potential.

Ethical and Scientific Perspective

Carrier screening is designed to inform, not to alarm. It helps individuals understand whether they carry gene variants that could be passed to future generations. The goal is to offer knowledge that empowers family planning and promotes healthy outcomes.

All testing is conducted under strict ethical standards, ensuring privacy, consent, and data protection at every stage. Genetic information is treated as educational and supportive, guiding parents and healthcare professionals in making informed reproductive choices.

Differences between Traditional Gene Analysis and Whole Genome Sequencing (WGS)

Why Phenome Longevity Testing Stands Apart

Scientific Rigor

Backed by state-of-the-art sequencing technology and our in-house systems biology expertise, ensuring accurate and reliable results.

Actionable Insights

We don't just provide data; we translate complex genetic information into clear, personalized recommendations for diet, lifestyle, and preventive measures.

Expert Genetic Counseling

Access to board-certified genetic counselors to help you understand your results and navigate sensitive health decisions with confidence.

Integrated Platform

Your genetic data is seamlessly integrated with our multi-omics platform, providing a holistic view of your health and supporting your longevity journey.

What's Included In Your Carrier Screening Report

Summary of Your Carrier Status

A clear overview of whether you carry any gene variants linked to inherited conditions. This section highlights all identified findings, including whether they are of clinical relevance and what type of inheritance pattern they follow.

Gene and Variant Details

Comprehensive information on the specific genes and variants analysed through next-generation sequencing (NGS). Each variant is classified based on clinical guidelines from ACGS and ClinGen, including gene coordinates, zygosity, and variant classification.

Condition-Specific Findings

Each detected variant is connected to its related medical condition, providing a concise summary of the disorder, associated risks, and inheritance pattern.

Inheritance Pattern Explanation

A simple and clear explanation of how genetic inheritance works, including autosomal dominant, autosomal recessive, and X linked patterns, to help you understand how results could affect you and your family.

Ethnicity Based Risk Context

Some genetic variants are more common in specific populations. This section places your results in context with global data, providing insight into carrier frequencies across different backgrounds.

Partner Screening Recommendations

When relevant, this section explains whether your partner should also be screened based on the inheritance type of any identified variants. Testing both partners helps determine if there is a potential risk for future children.

Residual Risk Explanation

Even with a negative result, a small residual risk may remain. This section explains why no test can fully eliminate risk due to genetic variability and evolving scientific knowledge.

Glossary and Scientific Notes

Definitions of key genetic terms and an outline of how results were interpreted. This section covers databases and classification systems such as ClinVar, gnomAD, ACGS, and ClinGen.

Explore the Genes We Screen For

The table below includes 115 genes, representing the most common ones screened in our Carrier Test. These genes are grouped into key health categories for easier navigation.

If you’d like to explore the full list of +1,000 genes included in our panel, click below.

Category	Most Important Genes We Identify	Examples of Disorders Linked
Metabolic Disorders	ACADM, ACADVL, ACAT1, AGXT, ALDOB, ATP7B, CYP27A1, CYP27B1, DHCR7, DLD, FAH, FMO3, G6PC, GAA, GALT, GBA, GBE1, GNPTAB, IDUA, MCCC2, MCOLN1, MMACHC, MMUT, MVK, NAGA, OTC, PAH, PMM2, POLG, SCO2, SLC37A4, SMPD1	Gaucher disease, Galactosemia, Phenylketonuria, Wilson disease, Glycogen storage diseases, Tyrosinemia, Pompe disease, Mucopolysaccharidoses, Mitochondrial disorders, Niemann–Pick disease
Neurological and Neurodevelopmental Disorders	AFF2, AHI1, ANO10, ARSA, ARX, ASPA, DMD, DYNC2H1, ELP1, ERCC2, FXN, L1CAM, MCPH1, MID1, MLC1, RARS2, RNASEH2B, RPGR, TMEM216	Duchenne/Becker muscular dystrophy, Friedreich ataxia, Joubert syndrome, Metachromatic leukodystrophy, Aicardi-Goutières syndrome, Canavan disease, Pontocerebellar hypoplasia
Neuromuscular Disorders	CHRNE, CLCN1, FKRP, FKTN, NEB	Congenital myasthenic syndromes, Myotonia congenita, Walker–Warburg syndrome, Limb-girdle muscular dystrophies, Nemaline myopathy
Hematological Disorders	F8, F9, HBA1, HBA2, HBB, FANCC, TF, PRF1, HPS1, HPS3	Hemophilia A/B, α- and β-thalassemia, Sickle cell anemia, Fanconi anemia, Hermansky–Pudlak syndrome, Atransferrinemia
Endocrine and Reproductive Disorders	AIRE, CYP11A1, CYP21A2, NR0B1, ABCC8	Congenital adrenal hyperplasia, Adrenal insufficiency, Autoimmune polyendocrinopathy, Neonatal diabetes
Skeletal and Connective Tissue Disorders	ALPL, EVC2, SLC26A2, TNXB	Hypophosphatasia, Chondroectodermal dysplasia (Ellis–van Creveld), Achondrogenesis Ib, Ehlers–Danlos-like syndrome
Sensory Disorders (Vision / Hearing)	BBS1, BBS2, CEP290, CNGB3, CLRN1, GJB2, OCA2, PCDH15, RS1, TYR, USH2A, XPC	Retinitis pigmentosa, Usher syndrome, Leber congenital amaurosis, Achromatopsia, Albinism, Non-syndromic deafness, Xeroderma pigmentosum
Renal Disorders	NPHS1, PKHD1, AGXT	Polycystic kidney disease, Finnish congenital nephrotic syndrome, Primary hyperoxaluria
Cardiovascular and Muscular Disorders	FKTN, FKRP, DMD, GLA	Dilated cardiomyopathy, Fabry disease, Muscular dystrophies
Immune and Inflammatory Disorders	AIRE, MVK, PRF1, RNASEH2B	Hyper-IgD syndrome, Autoimmune polyendocrinopathy, Familial hemophagocytic lymphohistiocytosis, Aicardi-Goutières syndrome
Dermatological and DNA-Repair Disorders	COL7A1, ERCC2, XPC	Epidermolysis bullosa, Trichothiodystrophy, Xeroderma pigmentosum
Developmental and Multisystem Syndromes	BBS1, BBS2, CC2D2A, CEP290, DYNC2H1, GRIP1, LRP2, TMEM216	Bardet-Biedl syndrome, Meckel syndrome, Joubert syndrome, Donnai–Barrow syndrome, Ciliopathies
Respiratory Disorders	ABCA3, CFTR	Surfactant metabolism dysfunction, Cystic fibrosis

How Our Test Kits Work

Step 01

Order a test and activate your kit

Step 02

Collect your sample

Step 03

Send your samples to our labs

Step 04

Get your results & consult our counsellor

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November 10, 2025
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Stories from Those Who Finally Got Answers

We are grateful to everyone who shared their journey with us. Their honesty reminds us why understanding our biology matters, because behind every test result there is a story of someone finally getting the answers they have been looking for.

My partner and I wanted to do this before trying for a baby. We were nervous at first, but the process felt surprisingly calm. Seeing our results side by side was a huge relief. It made us feel ready in a way that guessing never could.
— Emily and Noah S, 31

I’ve always been curious about my family health history, especially since no one really talks about it. The test made me realise I carry something I’d never have known otherwise. It wasn’t scary, just grounding to know.
— Julia M, 33

We went through this after a recommendation from our doctor. It was emotional but also empowering. Knowing what we carry doesn’t define us, it just helps us make choices with more confidence.
— Rachel L, 35

I was honestly scared to take the test, but the genetic counsellor explained everything so clearly that all my worries disappeared. It felt so personal and human, not technical at all. I left the call feeling grateful and confident about the future.
— Hannah C, 29