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Smith-Lemli-Opitz Syndrome

Table of Contents

Smith-Lemli-Opitz Syndrome

SLO syndrome; Smith Lemli Opitz syndrome; 7-Dehydrocholesterol reductase deficiency; RSH syndrome; SLOS; Rutledge lethal multiple congenital anomaly syndrome

Smith-Lemli-Opitz syndrome is a developmental disorder that affects many parts of the body. Severe cases can be life-threatening and involve profound intellectual disability and major physical abnormalities.

7-Dehydrocholesterol

Image by Ed (Edgar181)

Summary

Feets with partial simple syndactyly

Image by AzaToth

Feets with partial simple syndactyly

Syndactyly of the second and third toes

Image by AzaToth

What Is Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz syndrome (SLOS) is a rare genetic condition affecting multiple body systems. Signs and symptoms may include characteristic facial features, small head size, growth and developmental delays, and intellectual and behavioral problems. Individuals with SLOS have abnormally low levels of cholesterol in their blood and high levels of a chemical known as 7-dehydrocholestrol. The severity of symptoms varies from individual to individual. Many babies have feeding difficulties and growth issues. Some are born with heart, kidney, and adrenal problems. Most people with SLOS have some degree of intellectual and behavioral difficulties. This condition is caused by genetic changes (DNA variants) in the DHCR7 gene and is inherited in an autosomal recessive pattern. This condition is diagnosed based on the features and laboratory and genetic testing. Treatment is based on the symptoms.

Source: Genetic and Rare Diseases (GARD) Information Center

Additional Materials (3)

Smith-Lemli-Opitz Syndrome - CRASH! Medical Review Series

Video by Paul Bolin, M.D./YouTube

Smith Lemli Opitz Syndrome 101

Video by Smith-Lemli-Opitz Foundation/YouTube

Nutrition in Smith Lemli Opitz Syndrome

Video by Smith-Lemli-Opitz Foundation/YouTube

26:45

Smith-Lemli-Opitz Syndrome - CRASH! Medical Review Series

Paul Bolin, M.D./YouTube

44:52

Smith Lemli Opitz Syndrome 101

Smith-Lemli-Opitz Foundation/YouTube

31:51

Nutrition in Smith Lemli Opitz Syndrome

Smith-Lemli-Opitz Foundation/YouTube

Symptoms

Microcephaly

Image by CDC

Microcephaly

Normal Baby head compared to baby with microcephaly

Image by CDC

What Are the Signs and Symptoms of Smith-Lemli-Opitz Syndrome?

Signs and symptoms of Smith-Lemli-Opitz syndrome may include:

Microcephaly
Intellectual disability
Global developmental delay
Distinctive facial features
Feeding difficulties
Cleft palate
Underdeveloped male genitalia
Defect in the opening of the penis (hypospadias)
Extra fingers and toes (Postaxial polydactyly)
Webbed toes (2-3 syndactyly)
Heart abnormalities

Newborns with Smith-Lemli-Opitz syndrome (SLOS) are often born with characteristic facial features, extra fingers and toes, and small chin with a cleft palate. Some have heart defects, feeding issues, and gastrointestinal problems. Children with SLOS have some degree of intellectual disability and behavioral issues, such as sleep disturbances. They are often very sensitive to sunlight. Lower levels of cholesterol and increased levels of a chemical known as 7-dehydrocholesterol (7DHC) are associated with more severe features and symptoms.

Source: Genetic and Rare Diseases (GARD) Information Center

Causes

Missense Mutation

Image by National Human Genome Research Institute (NHGRI)

Missense Mutation

A missense mutation is when the change of a single base pair causes the substitution of a different amino acid in the resulting protein.

Image by National Human Genome Research Institute (NHGRI)

What Causes Smith-Lemli-Opitz Syndrome?

DHCR7 gene.

Source: Genetic and Rare Diseases (GARD) Information Center

Additional Materials (1)

Missense mutation

This type of mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by a gene.

Image by U.S. National Library of Medicine

Missense mutation

U.S. National Library of Medicine

Inheritance

autosomal recessive pattern of inheritance

Image by Thomas Shafee and TheVisualMD

autosomal recessive pattern of inheritance

Newborn autosomal recessive pattern of inheritance

Image by Thomas Shafee and TheVisualMD

How Is Smith-Lemli-Opitz Syndrome Inherited?

People with autosomal recessive conditions inherit one changed gene from each of their parents. The parents are known as carriers. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When two carriers of an autosomal recessive condition have children, there is a 25% (1 in 4) chance to have a child with the condition.

Source: Genetic and Rare Diseases (GARD) Information Center

Diagnosis

Genetic testing

Image by genome.gov

Genetic testing

Genetic testing fact sheet

Image by genome.gov

How Is Smith-Lemli-Opitz Syndrome Diagnosed?

DHCR7 gene can confirm the diagnosis.

Source: Genetic and Rare Diseases (GARD) Information Center

Genetic Testing

Genetic Testing

Also called: DNA Testing, Mutation Screening, Genetic Test

Genetic testing is a type of test that analyze your cells or tissue to look for any changes in your DNA. Genetic tests may be used to identify increased risks of health problems, to choose treatments, or to assess responses to treatments.

Genetic Testing

Also called: DNA Testing, Mutation Screening, Genetic Test

Genetic testing is a type of test that analyze your cells or tissue to look for any changes in your DNA. Genetic tests may be used to identify increased risks of health problems, to choose treatments, or to assess responses to treatments.

{"label":"Genetic Test Reference Range","scale":"lin","step":0.25,"hideunits":true,"items":[{"flag":"negative","label":{"short":"Negative","long":"Negative","orientation":"horizontal"},"values":{"min":0,"max":1},"text":"A negative result means that the test did not find a genetic change known to cause disease. ","conditions":[]},{"flag":"borderline","label":{"short":"Uncertain","long":"Uncertain","orientation":"horizontal"},"values":{"min":1,"max":2},"text":"An uncertain result means that a variant of unknown or uncertain significance means there isn\u2019t enough information about that genetic change to determine whether it is benign (normal) or pathogenic (disease causing).","conditions":[]},{"flag":"positive","label":{"short":"Positive","long":"Positive","orientation":"horizontal"},"values":{"min":2,"max":3},"text":"A positive result means that the test found a genetic change known to cause disease.","conditions":[]}],"value":0.5}[{"negative":0},{"borderline":0},{"positive":0}]
Use the slider below to see how your results affect your health.
Your result is Negative.
A negative result means that the test did not find a genetic change known to cause disease.
Related conditions
Genetic testing may be done for many different reasons, including to:
- Find genetic diseases in unborn babies. This is one type of prenatal testing.
- Screen newborn babies for certain treatable conditions
- Lower the risk of genetic diseases in embryos that were created using assisted reproductive technology
- Find out if you carry a gene for a certain disease that could be passed on to your children. This is called carrier testing.
- See whether you are at increased risk of developing a specific disease. This may be done for a disease that runs in your family.
- Diagnose certain diseases
- Identify genetic changes that may be causing or contributing to a disease that you were already diagnosed with
- Figure out how severe a disease is
- Help guide your doctor in deciding the best medicine and dosage for you. This is called pharmacogenomic testing.
There are no known risks to having a saliva test. There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
The physical risks of the different types of genetic testing are small. But there can be emotional, social, or financial drawbacks:
- Depending on the results, you may feel angry, depressed, anxious, or guilty. This can be especially true if you are diagnosed with a disease that does not have effective treatments.
- You may be worried about genetic discrimination in employment or insurance
- Genetic testing may give you limited information about a genetic disease. For example, it cannot tell you whether you will have symptoms, how severe a disease might be, or whether a disease will get worse over time.
- Some genetic tests are expensive, and health insurance might only cover part of the cost. Or they may not cover it at all.
- Positive – the test found a genetic change known to cause disease.
- Negative – the test did not find a genetic change known to cause disease. Sometimes a negative result occurs when the wrong test was ordered or there isn’t a genetic cause for that person’s symptoms. A “true negative” is when there is a known genetic change in the family and the person tested did not inherit it. If your test results are negative and there is no known genetic change in your family, a negative test result may not give you a definite answer. This is because you might not have been tested for the genetic change that runs in your family.
- Uncertain – a variant of unknown or uncertain significance means there isn’t enough information about that genetic change to determine whether it is benign (normal) or pathogenic (disease causing).
1. Genetic Testing | CDC. Sep 23, 2022 [accessed on Feb 23, 2022]
2. Genetic Testing: MedlinePlus. National Library of Medicine. Jun 11, 2021 [accessed on Feb 23, 2022]
3. What is genetic testing?: MedlinePlus Genetics [accessed on Feb 23, 2022]
4. Genetic Testing FAQ. Genome.gov [accessed on Feb 23, 2022]
5. Genetic testing and your cancer risk: MedlinePlus Medical Encyclopedia [accessed on Feb 23, 2022]

Normal reference ranges can vary depending on the laboratory and the method used for testing. You must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

Additional Materials (21)

Genetic testing

Genetic testing fact sheet

Image by genome.gov

Genetic testing

Genetic testing existed before the Human Genome Project and the list of diseases that we can already screen for may be longer than you think.

Image by TheVisualMD

Genes and Genetic Defects

Genetic testing isn't new. In the 1960s, doctors were able to test newborn babies for certain rare single-gene disorders, such as phenylketonuria (PKU), a rare metabolic disease that causes mental retardation. (PKU can be prevented with a special diet if it's detected early, which was why it was critical to test newborns.)

Image by TheVisualMD

Mapping Your Future: Screening for Disease Risk

Image by TheVisualMD

Each person with Down syndrome has different talents and the ability to thrive.

Down syndrome is a lifelong condition. Services early in life will often help babies and children with Down syndrome to improve their physical and intellectual abilities. Most of these services focus on helping children with Down syndrome develop to their full potential. These services include speech, occupational, and physical therapy, and they are typically offered through early intervention programs in each state. Children with Down syndrome may also need extra help or attention in school, although many children are included in regular classes.

Image by CDC

genetic analysis

Biotechnology - DNA analysis and treatment

Image by OpenClipart-Vectors/Pixabay

Family history (medicine)

An extended family in Spain

Image by Ojedamd

Biotechnology

This diagram shows the basic method used for extraction of DNA.

Image by CNX Openstax

Genetic Counselor at Sanford Health Explains the Benefits to Genetic Testing

Video by Sanford Health/YouTube

What Is A Genetic Counselor & The Importance of Genetic Counselling | Ambry Genetics

Video by Ambry Genetics/YouTube

How Does The Genetic Testing Process Work? Genetic Testing FAQ | Ambry Genetics

Video by Ambry Genetics/YouTube

Should You Get Genetic Testing During Your Pregnancy?

Video by St. Louis Children's Hospital/YouTube

Debating Embryonic Genetic Testing -- The Doctors

Video by The Doctors/YouTube

Genetic Testing for Cancer — AMITA Health | NBC Chicago Ask the Doc

Video by AMITA Health/YouTube

MedGenome BRCA - Breast Cancer Genetic Testing

Video by MedGenome/YouTube

Genetic Testing for Hereditary Forms of Kidney Cancer - Brian Shuch, MD

Video by UCLA Health/YouTube

Do I need Genetic Testing for Ichthyosis?

Video by foundation for ichthyosis/YouTube

What Is Genetic Testing? Understanding the Process and Its Results

Video by uvahealth/YouTube

How to Understand Your Genetic Testing Results

Video by Breast Cancer Answers®/YouTube

Genetic Testing 101 for People with Rare Diseases

Video by National Organization for Rare Disorders (NORD)/YouTube

What's the difference between genetic and genomic testing?

Video by Cancer Treatment Centers of America - CTCA/YouTube

Genetic testing

genome.gov

Genetic testing

TheVisualMD

Genes and Genetic Defects

TheVisualMD

Mapping Your Future: Screening for Disease Risk

TheVisualMD

Each person with Down syndrome has different talents and the ability to thrive.

CDC

genetic analysis

OpenClipart-Vectors/Pixabay

Family history (medicine)

Ojedamd

Biotechnology

CNX Openstax

1:57

Genetic Counselor at Sanford Health Explains the Benefits to Genetic Testing

Sanford Health/YouTube

1:06

What Is A Genetic Counselor & The Importance of Genetic Counselling | Ambry Genetics

Ambry Genetics/YouTube

0:45

How Does The Genetic Testing Process Work? Genetic Testing FAQ | Ambry Genetics

Ambry Genetics/YouTube

3:04

Should You Get Genetic Testing During Your Pregnancy?

St. Louis Children's Hospital/YouTube

4:40

Debating Embryonic Genetic Testing -- The Doctors

The Doctors/YouTube

1:31

Genetic Testing for Cancer — AMITA Health | NBC Chicago Ask the Doc

AMITA Health/YouTube

2:10

MedGenome BRCA - Breast Cancer Genetic Testing

MedGenome/YouTube

1:37

Genetic Testing for Hereditary Forms of Kidney Cancer - Brian Shuch, MD

UCLA Health/YouTube

1:43

Do I need Genetic Testing for Ichthyosis?

foundation for ichthyosis/YouTube

2:01

What Is Genetic Testing? Understanding the Process and Its Results

uvahealth/YouTube

3:58

How to Understand Your Genetic Testing Results

Breast Cancer Answers®/YouTube

1:00:31

Genetic Testing 101 for People with Rare Diseases

National Organization for Rare Disorders (NORD)/YouTube

2:05

What's the difference between genetic and genomic testing?

Cancer Treatment Centers of America - CTCA/YouTube

Prenatal Genetic Screening

Prenatal Genetic Screening

Also called: Prenatal DNA Testing, Carrier Screening for Genetic Disorders

Genetic tests look at the genetic information, called DNA, carried inside a person’s cells. When genetic screening is done for a baby’s parents, it can determine if either or both of the parents carry genes for a disease or disorder that can be passed on to their child.

Prenatal Genetic Screening

Also called: Prenatal DNA Testing, Carrier Screening for Genetic Disorders

Genetic tests look at the genetic information, called DNA, carried inside a person’s cells. When genetic screening is done for a baby’s parents, it can determine if either or both of the parents carry genes for a disease or disorder that can be passed on to their child.

{"label":"Prenatal Genetic Screening Reference Range","scale":"lin","step":0.25,"hideunits":true,"items":[{"flag":"negative","label":{"short":"Negative","long":"Negative","orientation":"horizontal"},"values":{"min":0,"max":1},"text":"No genetic disorders found.","conditions":[]},{"flag":"positive","label":{"short":"Positive","long":"Positive","orientation":"horizontal"},"values":{"min":1,"max":2},"text":"Possible genetic disorder. Confirmatory testing may be required. Talk with your genetic counselor to find out more about your results.","conditions":["Genetic disorder"]}],"value":0.5}[{"negative":0},{"positive":0}]
Use the slider below to see how your results affect your health.
Your result is Negative.
No genetic disorders found.
Related conditions
You should consider genetic screening if:
- You or your partner has a family history of a specific genetic disorder, such as cystic fibrosis.
- You belong to an ethnic group in which a genetic disease is more common—for instance, sickle cell disease in African Americans.
- You will be 35 or older on your due date, as your chances of having a child with genetic abnormalities increase as you get older.
- You have experienced multiple miscarriages, because the presence of genetic abnormalities in the fetus may be causing the miscarriages.
1. https://arupconsult.com/content/carrier-screening-genetic-disorders [accessed on Sep 03, 2020]
2. https://medlineplus.gov/genetictesting.html [accessed on Jan 31, 2019]
3. https://www.acog.org/Patients/FAQs/Prenatal-Genetic-Screening-Tests?IsMobileSet=false [accessed on Jan 31, 2019]
4. https://kidshealth.org/en/parents/genetics.html [accessed on Jan 31, 2019]
5. https://www.stanfordchildrens.org/en/topic/default?id=uses-of-genetic-testing-90-P02160 [accessed on Jan 31, 2019]
6. https://www.mayoclinic.org/tests-procedures/genetic-testing/about/pac-20384827 [accessed on Jan 31, 2019]

Normal reference ranges can vary depending on the laboratory and the method used for testing. You must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

Additional Materials (8)

Prenatal Screening and Genetic Testing: Expert Q&A

Video by UChicago Medicine/YouTube

Understanding options for expanding prenatal genetic screening with non-invasive prenatal testing

Video by Illumina/YouTube

Stanford Hospital's Dr. Jane Chueh on Prenatal Screening and Diagnosis

Video by Stanford Health Care/YouTube

An introduction to genetics & prenatal genetic testing

Video by Illumina/YouTube

Prenatal testing for chromosomal abnormalities

Video by Northwell Health/YouTube

Understanding Prenatal Screening and Testing Options at OSU Maternal Fetal Medicine

Video by Ohio State Wexner Medical Center/YouTube

Prenatal Testing

Video by Stanford Children's Health | Lucile Packard Children's Hospital Stanford/YouTube

Noninvasive Prenatal Screening Patient Education Animation

Video by Myriad Women's Health/YouTube

28:07

Prenatal Screening and Genetic Testing: Expert Q&A

UChicago Medicine/YouTube

3:46

Understanding options for expanding prenatal genetic screening with non-invasive prenatal testing

Illumina/YouTube

1:11:38

Stanford Hospital's Dr. Jane Chueh on Prenatal Screening and Diagnosis

Stanford Health Care/YouTube

3:21

An introduction to genetics & prenatal genetic testing

Illumina/YouTube

3:32

Prenatal testing for chromosomal abnormalities

Northwell Health/YouTube

14:57

Understanding Prenatal Screening and Testing Options at OSU Maternal Fetal Medicine

Ohio State Wexner Medical Center/YouTube

20:52

Prenatal Testing

Stanford Children's Health | Lucile Packard Children's Hospital Stanford/YouTube

2:39

Noninvasive Prenatal Screening Patient Education Animation

Myriad Women's Health/YouTube

Treatment

Total Cholesterol Rotation (HDL, LDL, and VLDL Molecules)

Image by TheVisualMD

Total Cholesterol Rotation (HDL, LDL, and VLDL Molecules)

A test for total cholesterol is an overall measure of “good” as well as “bad” cholesterol. A lipoprotein (from the Greek lipos, for fat) is a fat-and-protein package that enables fats and cholesterol to move freely within the bloodstream (fats and blood, like oil and water, do not mix). Proteins and other components make up the outer shell of the lipoprotein; cholesterol and other fats are packed together inside. The size and density of the lipoprotein determines whether its cholesterol is classified as “good” or “bad.” This interactive features 3 lipoproteins: very high density lipoprotein (VLDL) which is the largest molecule, low-density lipoproteins (LDL) which is the medium-sized molecule, and high-density lipoproteins (HDL), which are the smallest and most dense.

Image by TheVisualMD

How Might Smith-Lemli-Opitz Syndrome Be Treated?

Some of the specialists who may be involved in the care of someone with Smith-Lemli-Opitz syndrome include:

Genetics specialist
Gastroenterologist
Neurologist
Cardiologist
Dietitian or nutritionist

Source: Genetic and Rare Diseases (GARD) Information Center

Prognosis

Treatment and Prognosis varies depending on the type of condition and the age of symptom onset.

Image by 4144132

Treatment and Prognosis varies depending on the type of condition and the age of symptom onset.

Prognosis varies depending on the type of MND and the age of symptom onset.

Image by 4144132

What Is the Long-Term Outlook for People with Smith-Lemli-Opitz Syndrome?

A person with Smith-Lemli-Opitz syndrome who has appropriate medical care and follows a proper diet has the potential for a normal life expectancy. Independent living is unlikely, however, due to the presence of intellectual disability. Children with the most severe cases of Smith-Lemli-Opitz syndrome (those who produce little or no cholesterol) often die within a few months of birth.

Source: Genetic and Rare Diseases (GARD) Information Center

Statistics

Populations - How Common

Image by geralt/Pixabay

Populations - How Common

Image by geralt/Pixabay

How Common Is Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz syndrome affects an estimated 1 in 40,000 to 1 in 70,000 newborns in North America. The exact incidence of this condition is unknown.

Source: Genetic and Rare Diseases (GARD) Information Center

Related HealthJournals

Genetic Testing

Genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. Over 2000 tests are available. Genetic testing may be done for many reasons, from newborn baby screening to diagnosing certain diseases. Read about why you might consider testing.

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Smith-Lemli-Opitz Syndrome

Smith-Lemli-Opitz syndrome is a developmental disorder that affects many parts of the body. Severe cases can be life-threatening and involve profound intellectual disability and major physical abnormalities.

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