Clinical Trial: Simvastatin Therapy in Smith-Lemli-Opitz Syndrome

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Investigation of Simvastatin Therapy in Smith-Lemli-Opitz Syndrome

Brief Summary:

This study will evaluate the safety and effectiveness of simvastatin in treating children with Smith-Lemli-Opitz syndrome (SLOS). Patients with this inherited disease are deficient in an enzyme that converts a substance called 7-dehydrocholesterol (7-DHC) to cholesterol. Cholesterol synthesis is impaired, causing birth defects and mental retardation. This study will examine whether simvastatin can increase the amount of the deficient enzyme, thereby lowering 7-DHC and increasing cholesterol. It will examine the safety of simvastatin in affected children and its effects on their behavioral problems.

Children between 4 and 18 years of age with mild to typical SLOS may be eligible for this study. Participants will be evaluated at the NIH Clinical Center in Bethesda, MD, and at the Kennedy Krieger Institute in Baltimore, MD, upon admission to the study and again at 6, 12, 20, and 26 months. The visits will last 3 to 4 days, and will include a medical history and physical examination, photographs to document medical findings, and other procedures detailed below. In addition, blood samples will be collected at 1, 3, 9, 14, 15, 17, and 23 months. Parents will complete several questionnaires during the study. Procedures include the following:

  • Simvastatin and cholesterol supplementation therapy. Patients take cholesterol supplements (50 milligrams per kilogram per day) plus simvastatin (0.5 mg/kg/day for 6 weeks and then 1 mg/kg/day) for 12 months, and cholesterol supplements plus a placebo for 12 months.
  • Blood draws to check liver, muscle, and kidney function, hormone levels, vitamin D levels, blood counts, cholesterol and 7-DHC levels, and lipoprotein levels. Some extra blood is drawn for research purposes.
  • Urine collection. Urin

    Detailed Summary: Smith-Lemli-Opitz syndrome (SLOS, RSH, OMIM #270400) is an autosomal recessive, multiple malformation, mental retardation syndrome due to an inborn error of cholesterol biosynthesis. Specifically, these patients have a deficiency of 3 beta-hydroxysterol Delta 7-reductase activity due to mutation of the 3 beta-hydroxysterol delta 7-reductase gene (DHCR7). This enzymatic deficiency impairs the conversion of 7-dehydrocholesterol (7-DHC) to cholesterol in the last step of cholesterol biosynthesis via the Kandutch-Russel biosynthetic pathway. The clinical manifestations of SLOS are extremely variable and the phenotypic spectrum is broad. At the severe end of the spectrum SLOS is a lethal disorder with multiple major congenital anomalies, and in mild cases SLOS combines minor physical stigmata with behavioral and learning disabilities. Based on clinical studies, the incidence of SLOS is on the order of 1/10,000 to 1/60,000. Molecular studies have shown a carrier frequency of about 1% for the most common SLOS mutant allele in North American populations. Currently therapy is based on dietary cholesterol supplementation. Although clinical improvement has been noted, serum cholesterol levels are rarely normalized and elevated serum 7-DHC levels persist. Because elevated 7-DHC levels may have toxic effects, treatment of SLOS patients with an HMG-CoA reductase inhibitor has been proposed. Two small (two-patient) open trials of simvastatin therapy in SLOS have been reported. One of these trials showed improved clinical status, decreased 7-DHC levels and increased cholesterol levels. The second trial showed decreased 7-DHC levels; however, treatment had to be discontinued in one patient with preexisting liver disease. The goal of this clinical research protocol will be to test the clinical efficacy and safety of simvastatin therapy in mild to classical SLOS patients using a double blinded, crossover design.
    Sponsor: Forbes Porter, M.D.

    Current Primary Outcome: Serum Cholesterol to Total Sterol Ratio [ Time Frame: 1 year after therapy. ]

    Total serum cholesterol (mg/dL) divided by the sum of all sterols (cholesterol plus its precursors, 7-dehydrocholesterol - 7DHC, and 8-dehydrocholesterol- 8DHC - in mg/dL).


    Original Primary Outcome:

    Current Secondary Outcome: Cerebral Spinal Fluid Dehydrocholesterol to Total Sterol Ratio [ Time Frame: 12 months ]

    Percent of 7-dehydrocholesterol + 8-dehydrocholesterol as a fraction of the total sterols (cholesterol + 7-dehydrocholesterol + 8-dehydrocholesterol measured in cerebral spinal fluid


    Original Secondary Outcome:

    Information By: National Institutes of Health Clinical Center (CC)

    Dates:
    Date Received: July 11, 2003
    Date Started: July 2003
    Date Completion:
    Last Updated: June 4, 2014
    Last Verified: June 2014