Also known as: SLO syndrome; RSH syndrome; Rutledge lethal multiple congenital anomaly syndrome; Polydactyly, Sex reversal, renal hypoplasia, and unilobar lung; Lethal acrodysgenital syndrome


1. The Disease:

Smith-Lemli-Opitz syndrome (SLOS) is a congenitalmultiple-anomaly/ cognitive impairment syndrome caused by an abnormality in cholesterol metabolism resulting from deficiency of the enzyme 7-dehydrocholesterol (7-DHC) reductase.

2. The symptoms:

It is characterized by prenatal and postnatal growth restriction, microcephaly, moderate-to-severe intellectual disability, and multiple major and minor malformations. The malformations include distinctive facial features, cleft palate, cardiac defects, underdeveloped external genitalia in males, postaxial polydactyly, and 2-3 syndactyly of the toes. The clinical spectrum is wide; individuals with normal development and only minor malformations have been described.

3. Actions to take in case of early diagnosis:

Biochemical correlation is recommended with low levels of cholesterol in 90% of the patients and elevated 7-dehydrocholesterol level in all cases.

SLO is a lifelong disease requiring lifetime management and regular follow-up with a Paediatric Neurology Center Management is provided by multidisciplinary team.

While no long-term dietary studies on cholesterol supplementation have been conducted in a randomized fashion, cholesterol supplementation may result in clinical improvement.

Consultation with a nutritionist and consideration of hypoallergenic or elemental formulas in infants; neonatal cholestatic liver disease often resolves with cholesterol and/or bile acid therapy.

Proper clothing and sunscreen with UVA and UBV protection for photosensitivity.

In the presence of adrenal insufficiency, including stress-related doses of steroids during illness and other physical stress.

Agents/circumstances to avoid: Treatment with haloperidol or other drugs in the same class. Psychotropic drugs (trazodone, aripiprazole) that elevate 7-DHC should be used with caution; extended sun exposure should be avoided.

Genetic counselling is highly recommended for family planning and evaluation of at-risk family members such as siblings.

4. For more information: