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Smith-Lemli-Opitz syndrome: a variable clinical and biochemical phenotype
A K Ryan1, K Bartlett, P Clayton
1Department of Human Genetics, University of Newcastle upon Tyne, UK.
Journal of Medical Genetics
|July 25, 1998
Summary
Smith-Lemli-Opitz syndrome (SLOS) affects 1 in 60,000 UK births, with half of cases not surviving infancy. Key features include hypospadias, short thumbs, photosensitivity, and behavioral issues.
Area of Science:
- Genetics
- Metabolic Disorders
- Pediatrics
Background:
- Smith-Lemli-Opitz syndrome (SLOS) is a rare genetic disorder caused by 7-dehydrocholesterol reductase deficiency.
- It leads to impaired cholesterol synthesis and affects multiple organ systems.
Purpose of the Study:
- To review all known UK cases of SLOS.
- To determine the incidence, clinical features, and survival rates of SLOS in the UK population.
Main Methods:
- Retrospective review of 49 confirmed UK cases of SLOS with 7-dehydrocholesterol reductase deficiency.
- Analysis of clinical data, including survival, physical features, and biochemical markers.
Main Results:
- Minimum incidence of SLOS in the UK is 1 in 60,000.
- 50% of diagnosed cases were terminated or died in infancy.
- Common features include hypospadias (71% male cases), short thumbs, severe photosensitivity, aggressive behavior, and atrioventricular septal defects.
- Facial features become less distinct with age; 20% lacked 2/3 toe syndactyly.
- Serum 7-dehydrocholesterol levels did not correlate with clinical severity.
Conclusions:
- SLOS has a significant impact on survival, with a notable male predominance likely due to hypospadias.
- Clinical presentation is variable, and some classic features may be absent.
- Biochemical markers alone are insufficient to predict SLOS clinical severity.