Dietary cholesterol supplementation and inhibitory factor 1 serum levels in two dizygotic Smith-Lemli-Opitz syndrome twins: a case report.

BACKGROUND: Smith-Lemli-Opitz syndrome (SLOS) is a rare genetic neurodevelopmental disorder caused by the defect in the 7-dehydrocholesterol reductase. This defect leads to the deficiency of cholesterol biosynthesis with accumulation of 7-dehydrocholesterol. Inhibitory factor 1 (IF1) is a well-known mitochondrial protein. Recently, it has been discovered in the human serum where it is reported to be involved in the HDL-cholesterol intake. Here we report the IF1 presence in the serum of two paediatric SLOS dizygotic twins treated with dietary cholesterol supplementation. CASE PRESENTATION: The patients showed a typical phenotype. They started dietary supplementation with cholesterol when 2 months old. The cholesterol intake was periodically titrated on the basis of weight increase and the twin 1 required a larger supplementation than the twin 2 during the follow-up. When 6.4-year-old, they underwent IF1 assay that was 7-fold increased in twin 2 compared to twin 1 (93.0 pg/ml vs 13.0 pg/ml, respectively). CONCLUSIONS: We report, for the first time, the presence of circulating IF1 in the serum of SLOS patients, showing different levels among them. Our findings confirm that IF1 could be a novel research target in cholesterol-related disorders and also in SLOS, and could contribute to the general debate on IF1 as a new modulator of cholesterol levels.

Treatment of Smith-Lemli-Opitz syndrome and other sterol disorders.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive genetic condition with a broad phenotype that results from deficiency of the final enzyme of the cholesterol synthesis pathway. This defect causes low or low-normal plasma cholesterol levels and increased 7- and 8-dehydrocholesterol (DHC) levels. Many therapies for SLOS and other disorders of sterol metabolism have been proposed, and a few of them have been undertaken in selected patients, but robust prospective clinical trials with validated outcome measures are lacking. We review the current literature and expert opinion on treatments for SLOS and other selected sterol disorders, including dietary cholesterol therapy, statin treatment, bile acid supplementation, medical therapies, and surgical interventions, as well as directions for future therapies and treatment research.

Analysis of short-term behavioral effects of dietary cholesterol supplementation in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is an inborn error of cholesterol synthesis due to mutations of 7-dehydrocholesterol reductase (DHCR7). DHCR7 catalyzes the reduction of 7-dehydrocholesterol (7DHC) to yield cholesterol in the final step of cholesterol biosynthesis. Phenotypically patients with SLOS have multiple malformations, cognitive deficits, and behavioral difficulties. Impaired DHCR7 activity results in the accumulation of 7DHC and frequently decreased cholesterol in blood and tissues. Dietary cholesterol supplementation has become standard therapy for SLOS, and anecdotal reports suggest rapid, marked clinical improvement of behavior problems. Although reported in the literature, beneficial behavioral effects of dietary cholesterol supplementation have not been formally documented through a randomized clinical trial. To address this we initiated a double-masked, placebo-controlled, cross-over trial to test the hypothesis that dietary cholesterol supplementation has rapid beneficial effects on behavior. Our primary outcome measure was the hyperactivity subscale of the Aberrant Behavior Checklist (ABC). Hyperactivity is a symptom that has been reported to respond rapidly to dietary cholesterol supplementation. Secondary outcome measures included the total ABC score and other ABC subscale scores. Ten subjects completed this study. Although the trial was done under conditions similar to those reported to induce marked behavioral changes in SLOS patients, we observed no differences between treatment and placebo phases. The results of this study call into question anecdotal reports supporting rapid behavioral benefits previously reported for dietary cholesterol supplementation in SLOS and underscore the need for a larger placebo-controlled trial.

Effects of dietary cholesterol and simvastatin on cholesterol synthesis in Smith-Lemli-Opitz syndrome.

Deficient cholesterol and/or excessive 7-dehydrocholesterol (7-DHC) may be responsible for the pathology of Smith-Lemli-Opitz syndrome (SLOS). Both high-cholesterol diets given to ameliorate cholesterol deficiency while decreasing 7-DHC and cholesterol-enriched diets plus simvastatin to further decrease sterol synthesis have been used as potential therapies. However, the effect of dietary cholesterol and simvastatin on cholesterol synthesis in SLOS has not been reported. Twelve subjects with SLOS enrolled in the study: Nine had received a high cholesterol diet (HI) for 3 y and three were studied after 4 wk on a low cholesterol diet (LO). Cholesterol fractional synthesis rate (FSR) was measured after oral administration of deuterium oxide, using gas chromatography isotope ratio mass spectrometry. FSR was lower in HI compared with LO (HI: 1.46 +/- 0.62%/d; LO: 4.77 +/- 0.95%/d; p < 0.001). Three HI subjects were retested after 0.8 y taking simvastatin (HI + ST). Simvastatin tended to reduce FSR and significantly decreased (p < 0.01) plasma 7-DHC compared with cholesterol supplementation alone. The study demonstrates the utility of the deuterium incorporation method to understand the effect of therapeutic interventions in SLOS. The data suggest that dietary cholesterol supplementation reduces cholesterol synthesis in SLOS and further support the rationale for the combined treatment of SLOS with a cholesterol-enriched diet and simvastatin.

Plasma plant sterol levels do not reflect cholesterol absorption in children with Smith-Lemli-Opitz syndrome.

OBJECTIVE: To test the hypothesis that there is a correlation between the ratio of plant sterols to cholesterol in plasma and dietary cholesterol absorption in children with Smith-Lemli-Opitz syndrome (SLOS), a cholesterol synthesis disorder. STUDY DESIGN: We obtained measurements of cholesterol absorption with a direct radioisotope cholesterol absorption method during 9 visits of children with SLOS. We measured plasma sterols in 22 children with SLOS and 16 control children, and we measured dietary intake of cholesterol and sitosterol (n=11 SLOS). RESULTS: The correlations of 2 plasma plant sterol ratios (sitosterol/cholesterol and campesterol/cholesterol) with direct cholesterol absorption measurement were poor (R= -0.33 and R= -0.25, respectively), significantly lower than the published correlation in adults (R=0.73; P< .02). CONCLUSIONS: Although the ratios of plant sterols to cholesterol in plasma has been used as a surrogate for cholesterol absorption in adults and children, these ratios may not accurately reflect cholesterol absorption in children with SLOS. These ratios should not be used as a surrogate for cholesterol absorption in children without further validation.

Partial rescue of retinal function and sterol steady-state in a rat model of Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS) is the first-described in a growing family of hereditary defects in cholesterol biosynthesis, and presents with a spectrum of serious abnormalities, including multiple dysmorphologies, failure to thrive, cognitive and behavioral impairments, and retinopathy. Using a pharmacologically induced rat model of SLOS that exhibits key hallmarks of the disease, including progressive retinal degeneration and dysfunction, we show that a high-cholesterol diet can substantially correct abnormalities in retinal sterol composition, with concomitant improvement of visual function, particularly within the cone pathway. Although histologic degeneration still occurred, a high-cholesterol diet reduced the number of pyknotic photoreceptor nuclei, relative to animals on a cholesterol-free diet. These findings demonstrate that cholesterol readily crosses the blood-retina barrier (unlike the blood-brain barrier) and suggest that cholesterol supplementation may be efficacious in treating SLOS-associated retinopathy.

Increased nonsterol isoprenoids, dolichol and ubiquinone, in the Smith-Lemli-Opitz syndrome: effects of dietary cholesterol.

Smith-Lemli-Opitz syndrome (SLOS) is an inherited autosomal recessive cholesterol deficiency disorder. Our studies have shown that in SLOS children, urinary mevalonate excretion is normal and reflects hepatic HMG-CoA reductase activity but not ultimate sterol synthesis. Hence, we hypothesized that in SLOS there may be increased diversion of mevalonate to nonsterol isoprenoid synthesis. To test our hypothesis, we measured urinary dolichol and ubiquinone, two nonsterol isoprenoids, in 16 children with SLOS and 15 controls, all fed a low-cholesterol diet. The urinary excretion of both dolichol (P < 0.002) and ubiquinone (P < 0.02) in SLOS children was 7-fold higher than in control children, whereas mevalonate excretion was comparable. In a subset of 12 SLOS children, a high-cholesterol diet decreased urinary mevalonate excretion by 61% (P < 0.001), dolichol by 70% (P < 0.001), and ubiquinone by 67% (P < 0.03). Our hypothesis that in SLOS children, normal urinary mevalonate excretion results from increased diversion of mevalonate into the production of nonsterol isoprenoids is supported. Dietary cholesterol supplementation reduced urinary mevalonate and nonsterol isoprenoid excretion but did not change the relative ratios of their excretion. Therefore, in SLOS, a secondary peripheral regulation of isoprenoid synthesis may be stimulated.

A case of Smith-Lemli-Opitz Syndrome, defect of cholesterol biosynthesis.

We report the case of a child with Smith-Lemli-Opitz Syndrome. The pregnancy was complicated by prenatal growth retardation. The baby was admitted to the Neonatal Intensive Care Unit of Chieti when she was five months old. She showed postnatal growth retardation, trouble sucking and swallowing, microcephaly and multiple major and minor malformations, including characteristic facial features and 2-3 syndactyly of the toes. We found correlations between multiple congenital malformations, failure to thrive and low plasmatic cholesterol measurement.

Intestinal absorption of cholesterol by patients with Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS) is a disorder of impaired cholesterol biosynthesis because of a deficiency of the enzyme 7-dehydrocholesterol-Delta(7)-reductase, in the last step in cholesterol biosynthesis. Dietary cholesterol has been proposed as a potential therapy for SLOS and is being tested currently. Because there is no information on cholesterol absorption in SLOS, we recruited 12 SLOS patients into the General Clinical Research Center for 1-wk periods for administration of test meals and for blood and stool collections. A test breakfast that contained tracer cholesterol-4-C(14) with egg yolk or with crystalline cholesterol in suspension was given subsequently. Twenty-four and 48-h blood and 1-wk stool samples then were collected. The radioactivities in these samples were analyzed to determine the absorption of cholesterol by these patients. In 11 patients who were given egg yolk cholesterol, cholesterol absorption was 27.3 +/- 6.7%. The absorption was slightly less at 20.5 +/- 10.3% but not significantly different for the six patients who were given crystalline cholesterol. There was a positive correlation between the absorption of isotopic cholesterol as measured by determination of radioactive cholesterol in stool and the amount of isotopic cholesterol in the plasma at 24 and 48 h after the meal. Our data indicated that SLOS patients absorb cholesterol from the diet. However, the percentage of absorption is lower than reported values for normal adults and for hypercholesterolemic children. The absorption of crystalline cholesterol in suspension was slightly lower than the absorption of cholesterol in egg yolk cholesterol by these patients. The absorption of cholesterol may ameliorate some of the biochemical and developmental deficits in SLOS patients.

Effects of dietary cholesterol on plasma lipoproteins in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome is a condition of impaired cholesterol synthesis that is caused by mutations in DHCR7 encoding 7-dehydrocholesterol-Delta7 reductase. Birth defects and mental retardation are characteristic. Deficient plasma and tissue cholesterol and excess cholesterol precursors 7 and 8 dehydrocholesterol (7DHC and 8DHC) contribute to the pathogenesis. Cholesterol is transported to tissues via lipoproteins. We measured the effect of dietary cholesterol (egg yolk) on plasma lipoproteins to evaluate this potential treatment. We used the enzymatic method to measure total sterols in lipoproteins (n=12) and plasma (n=16). In addition, we analyzed individual plasma sterols by a gas chromatographic method. Samples were evaluated after 3 wk of a cholesterol-free diet and after 6-19 mo of dietary cholesterol. We also analyzed the distribution of sterols in lipoproteins and the apolipoprotein E genotype. Dietary cholesterol significantly increased the total sterols in plasma (2.22 +/- 0.13 to 3.10 +/- 0.22; mean +/- SEM; p < 0.002), in LDL (0.98 +/- 0.13 to 1.52 +/- 0.17 mM), and in HDL (0.72 +/- 0.04 to 0.92 +/- 0.07). Plasma cholesterol increased (1.78 +/- 0.16 to 2.67 +/- 0.25 mM; p < 0.007) and plasma 7DHC decreased in 10 children, but the mean decrease was not significant. The distribution of individual sterols in each lipoprotein fraction was similar to the distribution in plasma. The baseline cholesterol and the response to dietary cholesterol was the same in children with 3/3 and 3/4 apolipoprotein E genotypes. Dietary cholesterol increased total sterols in plasma, LDL, and HDL in children with Smith-Lemli-Opitz syndrome. These favorable increases in the lipoproteins are potentially therapeutic for this condition.

Cholesterol supplementation does not improve developmental progress in Smith-Lemli-Opitz syndrome.

OBJECTIVE: Smith-Lemli-Opitz syndrome (SLOS) results in multiple malformations, growth deficiency, and mental retardation. Cholesterol supplementation has been used for several years to treat symptoms of SLOS. We assessed the developmental progress of children and adolescents with SLOS over a 6-year period. STUDY DESIGN: Patients with SLOS (n=14) received continuous cholesterol supplementation as part of a longitudinal study. Assessment of their developmental progress in the areas of cognitive, motor, and adaptive skills occurred every 6 to 12 months. The progress of each subject over time and the progress of the group as a whole were analyzed by using a repeated-measures design and multiple t tests. RESULTS: Developmental quotients did not improve over time for children with SLOS receiving cholesterol. In addition, baseline cholesterol levels, rather than age when supplementation began or increase in cholesterol levels, best predicted developmental outcome. CONCLUSIONS: These results suggest that cholesterol supplementation in its current form does not improve the developmental progress of children and adolescents with SLOS.

Cholesterol treatment forever? The first Scandinavian trial of cholesterol supplementation in the cholesterol-synthesis defect Smith-Lemli-Opitz syndrome.

OBJECTIVES: To investigate if exogenous cholesterol affects sterol turnover in the cholesterol-synthesis defect Smith-Lemli-Opitz syndrome (SLOS) and if clinical effects justify long-time supplementation. The SLOS is caused by a deficiency of the enzyme 7-dehydrocholesterol-7-reductase with markedly reduced cholesterol levels and greatly increased levels of 7-dehydrocholesterol (7-DHC). DESIGN: Treatment with dietary cholesterol in patients with SLOS in a case series study. SETTING: All biochemical analyses were performed in one laboratory. The clinical follow-up was carried out by one of the authors (LS), a paediatric neurologist. SUBJECTS: Seven patients with biochemically verified SLOS have been diagnosed in Sweden and all of them are included in the study. INTERVENTIONS: Six patients were treated for 0.5-6 years orally with cholesterol and the bile acid taurocholate and one patient was supplemented with cholesterol only. MAIN OUTCOME MEASURES: In addition to cholesterol, 7- and 8-DHC, lathosterol was used as a marker of endogenous cholesterol synthesis and the patients were followed clinically. Nerve conduction velocities (NCV) were measured before treatment in all patients and a UVA-light test was performed in one of them. RESULTS: Lathosterol was initially increased by cholesterol supply in subjects with very low cholesterol levels with subsequent rise of 7- and 8-DHC. Photosensitivity clinically improved in all, verified by UVA-light testing in one. Progressive polyneuropathy improved, whilst stationary forms did not. CONCLUSION: Dietary cholesterol can up-regulate sterol turnover in severely affected patients. Although some specific features are treatable and verifiable by objective methods, data supporting life-long treatment dietary cholesterol in all SLO patients are still lacking.

Feedback inhibition of the cholesterol biosynthetic pathway in patients with Smith-Lemli-Opitz syndrome as demonstrated by urinary mevalonate excretion.

Smith-Lemli-Opitz syndrome (SLOS) is a genetic disorder characterized by low plasma cholesterol and high 7-dehydrocholesterol (7-DHC). Synthesis of cholesterol and 7-DHC and its metabolites is regulated by HMG-CoA reductase, whose activity can be measured by 24-h excretion of its product mevalonate. We devised a simple, non-invasive method for collecting 24-h urine in our subjects. With a background of a very low cholesterol diet, mean mevalonate excretion did not differ between controls and SLOS children, indicating that SLOS subjects have normal HMG-CoA reductase activity. In a short term feeding study, the effects of a high cholesterol diet in SLOS subjects include a significant 55% increase in plasma cholesterol levels and 39% decrease in mevalonate excretion and no change in plasma 7-DHC levels. However, in four SLOS subjects, fed a high cholesterol diet for 2-3 years, plasma cholesterol levels continued to increase, urinary mevalonate excretion remained low and total 7-DHC decreased significantly, likely from decreased total sterol synthesis. Thus, in SLOS subjects, HMG-CoA reductase activity was normal and was subject to normal cholesterol induced feedback inhibition. However, total sterol synthesis in SLOS may still be decreased because of increased diversion of mevalonate into the shunt pathway away from sterol synthesis.

Cholesterol supplementation objectively reduces photosensitivity in the Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz (SLO) affected children have multiple congenital physical and mental abnormalities; photosensitivity to ultraviolet A (UVA) has recently become a recognized feature. We present a patient with SLO and prominent photosensitivity in whom detailed phototesting has been performed at baseline and following 6 months of cholesterol supplementation. There was significant improvement in the symptoms of photosensitivity, confirmed objectively by phototesting and accompanied by partial correction of the biochemical abnormalities seen in SLO. This case report is the first to show that cholesterol supplementation in SLO can lead to an objective improvement in the associated photosensitivity.

Smith-Lemli-Opitz syndrome: the first malformation syndrome associated with defective cholesterol synthesis.

Smith-Lemli-Opitz syndrome (SLOS), an autosomal recessive condition with multiple malformations, mental retardation, and growth failure, results from markedly reduced activity of the final enzyme in the cholesterol biosynthetic pathway, 7-dehydrocholesterol reductase (DHCR7). Clinical signs vary in severity, ranging from fetal loss to holoprosencephaly with multiple malformations to isolated syndactyly. The biochemical defect in SLOS is a deficiency of DHCR7, which results in an abnormally low cholesterol level, and increased amounts of intermediates of sterol biosynthesis. Animal models currently exist through the use of cholesterol biosynthesis inhibitors, from which a great deal has been learned. Pregnant rats treated with inhibitors of DHCR7 yield pups that have abnormal sterol profiles and craniofacial abnormalities characteristic of severe SLOS. Biochemical testing of human patients can be performed using gas chromatography/mass spectroscopy (GC/MS) to analyze the sterol content of tissues, amniotic fluid, or cell culture lysate. Numerous mutations have been identified in DHCR7 but seven individual mutations account for 67% of the total mutations reported in the literature. Clinical trials with SLOS are underway, with the goal of increasing the cholesterol concentration in the plasma and tissues through the administration of dietary cholesterol. Thus far, this approach has shown limited efficacy. Nevertheless, the recent identification of the biochemical and molecular genetic basis for SLOS is reason for optimism that the condition may one day yield to treatment.

Smith-Lemli-Opitz syndrome: thirty-year follow-up of "S" of "RSH" syndrome.

We have reassessed patient "S," one of the first 3 individuals recognized to have Smith-Lemli-Opitz (or RSH) syndrome, at age 34 years, and we describe his physical, developmental, and behavioral manifestations. This reassessment provides formal evidence that this individual has the cholesterol biosynthetic defect which is thought to be the cause of Smith-Lemli-Opitz syndrome. Dietary manipulation appears to have had a beneficial effect on the patient's behavior and suggests that even in adults with this condition, dietary cholesterol supplementation may be indicated.