Although having low cholesterol in the body may sound healthy, it is not. Cholesterol is necessary for proper nerve functioning and for growth of the fetus. Fetuses severely affected by Smith-Lemli-Opitz syndrome are often miscarried, stillborn, or die shortly after birth.
Smith-Lemli-Opitz syndrome is an autosomal recessive disorder, meaning that an individual needs to inherit two copies of the defective gene in order to develop the disorder. Research on the incidence of SLOS has shown that it is more common in whites and individuals of Hispanic descent, and less common in those of African descent. The syndrome has been estimated to occur in 1 in 20,000-60,000 whites. The incidence may be higher due to unrecognized cases in miscarriages or in only mildly affected individuals.
Symptoms
Different individuals with Smith-Lemli-Opitz syndrome may have different symptoms, even within the same family, but some common symptoms may be:
- Unusual facial features such as broad nose, small lower jaw, and low-set ears
- Small head (microcephaly)
- Webbing (syndactyly) of the second and third toes
- Cleft palate (split in the roof of the mouth)
- Mental retardation or learning disabilities
- Behavior problems
Diagnosis
Smith-Lemli-Opitz syndrome is present from birth, but the physical symptoms may be so mild that it is not detected until the child is older or even an adult. Usually, though, SLOS is suspected because of the physical anomalies and the infant's difficulty feeding and poor weight gain. To confirm the diagnosis, a special blood sterol test is needed. Individuals with SLOS will have low cholesterol and high 7DHC levels in the blood.
Once Smith-Lemli-Opitz syndrome is identified, imaging studies such as magnetic resonance imaging (MRI) or ultrasonography can look for physical malformations such a heart defects. Hearing tests can assess any hearing loss.
Treatment and Research
Surgical repair of physical anomalies such as heart defects, cleft palate, or toe defects may be needed. It would seem logical that if low cholesterol is part of the problem, giving the individual a high-cholesterol diet should help. Early research evidence points in that direction; further studies need to be conducted to show if clear benefits from the diet exist.
Researchers are also considering cholesterol-lowering drugs called statins. In people with Smith-Lemli-Optiz syndrome, statins do not appear to lower blood cholesterol but instead lower levels of 7DHC. It might also be possible to correct 7DHC and cholesterol levels in utero, thus preventing some of the severe consequences of SLOS. Each of these research areas may hold promise for the future treatment of SLOS.
Information for this article was taken from:
Steiner, R. D. (2004). Smith-Lemli-Optiz syndrome. eMedicine, accessed at http://www.emedicine.com/ped/topic2117.htm
