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Weight Management with Smith-Lemli-Opitz Syndrome in South Africa

Smith-Lemli-Opitz Syndrome (SLOS) is one of the most counter-intuitive conditions in medicine — it is a cholesterol deficiency disorder in which the body cannot make enough cholesterol and accumulates a toxic precursor instead. In almost every other context, dietary cholesterol is something we are told to limit. In SLOS, adequate dietary cholesterol intake can be life-changing. This guide explains the unique nutritional needs of SLOS and how to manage weight and health in a South African context.

What Is Smith-Lemli-Opitz Syndrome?

SLOS is an autosomal recessive metabolic disorder caused by mutations in the DHCR7 gene, which encodes the enzyme 7-dehydrocholesterol reductase (DHCR7). This enzyme is responsible for the final step in cholesterol biosynthesis. When it is absent or deficient, the body:

SLOS occurs in approximately 1 in 20 000–60 000 births, though the carrier frequency is higher than this suggests. In South Africa, it is likely under-diagnosed due to limited newborn screening.

Clinical Features of SLOS

SLOS presents on a spectrum from mild (detectable only biochemically) to severe. Common features include:

The Dietary Challenge: The Opposite of Conventional Wisdom

Here is the critical principle that differentiates SLOS from every other condition on this website:

In SLOS, dietary cholesterol is therapeutic — not harmful. High-cholesterol foods like eggs, meat and full-fat dairy are beneficial, not restricted.

Because the body cannot synthesise adequate cholesterol endogenously, dietary cholesterol can partially bypass the defective enzyme and raise plasma cholesterol levels. Studies have shown cholesterol supplementation improves:

What "Cholesterol Supplementation" Means in Practice

Cholesterol supplementation in SLOS can be achieved in two ways:

  1. Dietary cholesterol: Maximising natural food sources of cholesterol in every meal
  2. Pharmaceutical cholesterol powder: Pure cholesterol powder (anhydrous cholesterol) mixed into food — available from compounding pharmacies in South Africa (compounding pharmacies in Johannesburg, Cape Town and Durban can prepare this on prescription)

Diet for SLOS in South Africa

High-Cholesterol Foods to Prioritise

The following foods provide the most dietary cholesterol and should be included at every meal for a person with SLOS:

What to Avoid

Weight Management Context in SLOS

The weight management challenge in SLOS is almost always the opposite of the typical weight-loss scenario:

Photosensitivity and Nutrition

SLOS patients are abnormally sensitive to sunlight because 7-DHC in the skin produces harmful reactive oxygen species when exposed to UV. This is particularly relevant in South Africa's high-UV environment.

Exercise and Physical Activity

Exercise for SLOS patients must be adapted to the individual's degree of intellectual and physical disability:

Simvastatin — Emerging Experimental Evidence

Note: A controversial area of SLOS research involves paradoxical use of low-dose simvastatin in some SLOS patients. The rationale is that simvastatin may reduce 7-DHC accumulation by a different mechanism. This is experimental and NOT standard practice. It should only ever be considered under the guidance of a metabolic disease specialist with deep SLOS expertise. Do not attempt this without specialist supervision.

Diagnosing SLOS in South Africa

SLOS is confirmed by:

SA Specialist Resources

Key Takeaways

Disclaimer: This article is for informational purposes only and does not constitute medical advice. SLOS is a complex metabolic disorder requiring specialist medical and dietitian supervision. Never alter a SLOS patient's diet or medications without guidance from a metabolic disease specialist. If you suspect SLOS in a child or adult, seek urgent referral to a genetic metabolic service.