How do I know if I have Smith-Lemli-Opitz Syndrome?

Smith-Lemli-Opitz syndrome (SLOS) is a rare, genetic metabolic disorder caused by an inability to produce enough cholesterol, which is essential for normal growth and development. Diagnosis is confirmed through specialized biochemical testing that measures 7-dehydrocholesterol levels in the blood, often prompted by a combination of physical features, developmental delays, and behavioral challenges.

What are the early signs and symptoms of Smith-Lemli-Opitz syndrome?

Because Smith-Lemli-Opitz syndrome affects multiple body systems, the presentation can vary significantly from person to person. Many individuals are diagnosed in infancy due to distinct physical markers, while those with milder forms may not be identified until later childhood. Common clinical indicators often include:

• Physical features: A small head size (microcephaly), drooping eyelids (ptosis), a short upturned nose, and syndactyly (webbing) of the second and third toes.


• Developmental milestones: Significant delays in reaching motor and speech milestones, often accompanied by intellectual disability.


• Feeding and growth: Difficulty feeding in infancy, failure to thrive, and poor weight gain despite adequate caloric intake.


• Behavioral patterns: Many patients with Smith-Lemli-Opitz syndrome exhibit irritability, sleep disturbances, and autistic-like behaviors.

How is Smith-Lemli-Opitz syndrome diagnosed?

If you or your child exhibit several of the symptoms mentioned above, it is vital to consult a clinical geneticist. The gold standard for diagnosing Smith-Lemli-Opitz syndrome is a plasma sterol analysis. This blood test measures the level of 7-dehydrocholesterol (7-DHC); in patients with this condition, the enzyme 7-dehydrocholesterol reductase is deficient, causing 7-DHC levels to be abnormally high and cholesterol levels to be low. Genetic testing to identify mutations in the DHCR7 gene is also commonly used to confirm the diagnosis and provide clarity for family planning.

When should I seek urgent medical evaluation?

While Smith-Lemli-Opitz syndrome is a lifelong condition, certain red flags require immediate medical attention. These include severe dehydration due to feeding difficulties, unexplained lethargy, or signs of acute metabolic stress. Because individuals with Smith-Lemli-Opitz syndrome are highly sensitive to sunlight due to their metabolic profile, any severe skin reactions or photosensitivity should be discussed with a pediatrician or dermatologist promptly.

How do I advocate for myself or my child?

Rare diseases like Smith-Lemli-Opitz syndrome are often overlooked in primary care settings because they are so uncommon. If you feel your concerns are being dismissed, do not hesitate to request a referral to a metabolic specialist or a medical geneticist. Bring a written log of symptoms, developmental observations, and family history to your appointment. Remember that you are an expert on your own or your child’s health; if a provider remains unconvinced, seeking a second opinion at a major academic medical center or a center specializing in rare metabolic disorders is a valid and often necessary step.

Next steps

• Schedule an appointment with a clinical geneticist to discuss biochemical screening (plasma sterol analysis).


• Keep a detailed diary of developmental milestones and physical symptoms to share with your medical team.


• Connect with the 61 other members of our Smith-Lemli-Opitz syndrome community at DiseaseMaps.org to share experiences and find support.


• Review resources from the Smith-Lemli-Opitz Foundation to understand current management strategies and clinical research opportunities.

Medical Disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Smith-Lemli-Opitz syndrome overview.


• Orphanet: Rare disease database entry for Smith-Lemli-Opitz syndrome (ORPHA:813).


• OMIM (Online Mendelian Inheritance in Man): 7-Dehydrocholesterol reductase deficiency (#270400).


• The Smith-Lemli-Opitz Foundation: Patient and family support resources.