Biochemical and Phenotypical Aspects of Smith-Lemli-Opitz Syndrome and Related Disorders of Cholesterol Metabolism

Study Description: The objective of this study is to characterize the natural history of Smith-Lemli-Opitz Syndrome (SLOS) and related disorders (such as lathosterolosis, desmosterolosis, X-linked dominant chondrodysplasia punctata (CDPX2), CHILD syndrome, HEM dysplasia, and Antley-Bixler syndrome) by collecting both crosssectional and longitudinal data on individuals with these conditions.

Our goal is to investigate genetic, biochemical, and clinical aspects of SLOS and related disorders in order to facilitate development and implementation of future therapeutic trials. This protocol consists of a main study and three sub-studies. The main study involves inperson evaluation of patients and carriers of SLOS and related disorders. The first sub-study includes collecting biorepository samples from patients and carriers of SLOS and related disorders. The second sub-study involves obtaining a telemedicine history and full review of systems for affected individuals with SLOS and related disorders. The third sub-study involves a survey of caregivers of

deceased individuals with SLOS, which will address questions regarding the deceased individual s medical history and inform causes of death. All questions in the survey will be regarding the deceased individual s medical history, none of the questions will be about the caregivers. This protocol will also maintain a database of information collected over the past two decades at the NIH on SLOS trial participants. All individuals with SLOS, related disorders and carriers will be eligible for enrollment.

Objectives: The primary objective of this study is to determine laboratory or clinical outcome measures that could be used in future therapeutic trials.

The secondary objectives of these studies are to define comorbidities and mortality of the disease, investigate the causes of mortality, identify potential participants for future therapeutic trials and evaluate possible laboratory outcome measures and biomarkers in carriers and suspected carriers.

Endpoints: Primary endpoints

• Phenotypic characterization of individuals with SLOS and related inborn errors of cholesterol synthesis. Define and characterize disease related morbidity and mortality.
• Establishing a biomaterial collection (Blood, urine, CSF, DNA/RNA and cell lines) corresponding to well-phenotyped individuals for biomarker discovery and characterization.

Secondary endpoints: Phenotypic history as well as blood and urine biomarkers in individuals heterozygous for pathogenic DHCR7 variants or pathogenic variants in cholesterol synthetic genes. Additional outcomes include assessments of bone health.

• INCLUSION CRITERIA:

Males or females of any age with any one of the following:

• Clinical, biochemical, or genetic diagnosis of Smith-Lemli-Opitz Syndrome OR
• Clinical, biochemical, or genetic diagnosis of desmosterolosis, lathosterolosis, CHILD syndrome, X-linked dominant chondrodysplasia type2 or another inborn error of cholesterol synthesis OR
• Clinical suspicion of an inborn error of cholesterol synthesis, metabolism or impaired cholesterol homeostasis. Clinical observations may include, but are not limited to lipid-laden macrophages, abnormal LDL, HDL, total cholesterol, triglycerides, abnormal lipid

electrophoresis, lipid storage in other tissues. OR

-Biologic parents of affected individuals or known carriers based on previously done genetic testing who are willing and able to provide samples of any or all of the following: blood, urine, a skin biopsy, and/or tissue derived from clinically indicated surgery or autopsy.

Exclusion criteria

• Affected individuals who cannot travel to the NIH because of their medical condition will be excluded from on-site participation. They may participate in the telemedicine or in the biomaterials parts of the study.
• Affected individuals who, in the opinion of the investigator, are unable to comply with the protocol or have medical conditions that would potentially increase the risk of participation will be excluded from on-site participation. They may participate in the telemedicine or in the

biomaterials parts of the study.

• Carrier adults who are unable to or unwilling to provide any of the following samples: Blood, urine, skin biopsy sample or tissue derived from clinically indicated surgery or skin biopsy.
• Female participants who are pregnant will be excluded from evaluations requiring sedation, radiation and LP. Total blood draw volumes will be kept at a minimum or if anemia of pregnancy is known, no blood will be taken for research testing.