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Understanding Smith-Lemli-Opitz Syndrome: The Importance of Genetic Carrier Screening

Understanding Smith-Lemli-Opitz Syndrome: The Importance of Genetic Carrier Screening


Have you ever wondered why some genetic conditions appear seemingly out of nowhere within a family? Smith-Lemli-Opitz Syndrome (SLOS) is a rare genetic disorder that often catches families off guard. But fret not; advancements in medical science, particularly in genetic carrier screening, can help identify at-risk couples even without a family history. This blog post will explore SLOS, its impact on individuals and families, and how genetic carrier screening can make a significant difference.

What is Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz Syndrome is a rare genetic disorder that affects the body's ability to produce cholesterol. Cholesterol plays a crucial role in the development and function of various organs and systems, including the brain. Individuals with SLOS have deleterious variations in the DHCR7 gene, which is responsible for producing an enzyme involved in cholesterol synthesis. As a result, cholesterol levels in the body are significantly reduced, leading to a wide range of physical, developmental, and cognitive challenges.

How common is SLOS?

Smith-Lemli-Opitz Syndrome (SLOS) is a rare genetic disorder, and its exact prevalence is estimated to be around 1 in 20,000 to 60,000 live births. It is an autosomal recessive condition, which occurs when an individual inherits two copies of the mutated gene, one from each parent.

To inherit SLOS, both parents must be carriers of the gene mutation without displaying symptoms. Carriers have only one copy of the mutated gene and typically do not experience any health issues related to the condition. Approximately 1 in 70 people are carriers of SLOS. When both reproductive partners are carriers, there is a 25% chance with each pregnancy that the child will inherit two copies of the mutated gene, leading to the development of SLOS.

It is important to note that SLOS can occur in any ethnic or racial group, and the risk of having a child with SLOS is the same for both genders. Genetic carrier screening can be valuable in identifying individuals who carry the gene mutation, even if they do not have a family history of the disorder, allowing for informed family planning decisions and appropriate medical support.

Symptoms and Impact

The symptoms and severity of SLOS can vary from person to person, but some common characteristics include:

Facial and physical abnormalities: Individuals with SLOS may have distinctive facial features, such as a small head, low-set ears, a cleft palate, and widely spaced eyes. They may also experience growth delays, weak muscle tone, and malformations of the hands, feet, and internal organs.

Developmental delays: Children with SLOS often experience delays in reaching developmental milestones, such as sitting, crawling, and walking. They may have intellectual disabilities and struggle with learning, speech, and communication skills.

Behavioural and emotional challenges: Individuals with SLOS may exhibit autistic-like behaviours, such as repetitive movements, difficulty with social interactions, and heightened sensory sensitivities. They may also have behavioural issues, including aggression and self-injurious behaviours.

Genetic Carrier Screening: The Importance of Identifying At-Risk Couples

Genetic carrier screening is a powerful tool that can help identify individuals who carry gene mutations for specific genetic conditions, such as SLOS, even if they do not show any signs or symptoms themselves. It involves testing for specific genetic variations that can be passed on to children. By screening potential parents before conception, healthcare professionals can provide crucial information and support to couples who may be at risk of having a child with a genetic disorder.

The Absence of Family History

Genetic conditions like SLOS may appear unexpectedly in a family with no prior history of the disorder. This can happen when both parents are carriers of the same gene mutation but are unaware of it. Carrier screening becomes especially important in these situations, as it helps identify at-risk couples before they conceive a child, enabling them to make informed decisions about family planning.

Preconception carrier screening can be done through a simple saliva sample. It examines the DNA of both partners to determine if they carry any gene mutations associated with genetic disorders. Suppose both parents are found to be carriers of the same mutation. In that case, they can explore various options with healthcare professionals, such as preimplantation genetic diagnosis (PGT-M), adoption, or other family planning methods.

Smith-Lemli-Opitz Syndrome is a rare genetic disorder that can profoundly impact individuals and families. However, with advancements in genetic carrier screening, we have the power to identify at-risk couples even in the absence of family history. By understanding the underlying genetic risks and making informed decisions, couples can take steps to ensure the health and well-being of their future children. Genetic carrier screening empowers individuals to make choices that can positively impact you can get started here.

Learn more

Ornithine transcarbamylase (OTC) deficiency is a rare X-linked genetic disorder. It is a urea cycle disorder. One of many disorders that affect the urea cycle and metabolism. OTC specifically relates to protein intake.

The severity and age of onset of OTC deficiency vary from person to person, even within the same family. A severe form of the disorder affects some infants, typically males, shortly after birth (neonatal period). A milder form of the disorder affects some children later in infancy.

Some women who are carriers may not experience abnormally high levels of ammonia (hyperammonemia) until pregnancy or delivery.

In the same way that you’ve got your mum’s eyes and your dad’s nose, we’ve been passing on genes from parent to child, forever.

However, family history is not a good predictor of whether a child has an increased risk of being born with a genetic condition. In fact, 90% of babies born with a genetic condition had no family history of it!

Eugene’s carrier screen is an at-home DNA test that helps you identify if you have a higher chance of having a child with a serious genetic condition. The best time to do this test is when you are thinking about getting pregnant or within the first trimester.

Our comprehensive carrier screening tests for over 260 genetic conditions., including common conditions like Cystic Fibrosis, Spinal Muscular Atrophy, Thalassemia, and Tay-Sachs disease.

For the full list of genes, we check for click here.

At Eugene we celebrate autonomy in healthcare. Our members can be self-referred or have a referral from a healthcare practitioner.

If you have been referred by a healthcare practitioner, there is a ‘referring doctor’ field that you can fill in to let us know that you’d like us to share your results with them.

If you are self-referred or have another practitioner that you’d like your results to be shared with, you are welcome to add their details there too.

You have full control and choice in your health at Eugene.

Most couples find out that they do not carry the same genetic conditions as their partner.

About 1 in 40 people find out that they have an increased likelihood of having a child with a genetic condition. In this case, there would be a 25% chance that they could have a child affected by the condition. Having this knowledge before or early in pregnancy opens up your options.

For example, in pre-pregnancy, some couples may consider using donors or IVF technologies to conceive. If you are already pregnant, there may be the option of testing a pregnancy to see if the baby has inherited the associated genetic condition. Some couples may choose to not test before or during pregnancy, and instead use the knowledge of their carrier status to prepare for the birth of their child.

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