Smith–Lemli–Opitz syndrome
an inborn error of cholesterol synthesis, caused by a mutation in the enzyme 7-Dehydrocholesterol reductase
Smith–Lemli–Opitz syndrome is an inborn error of cholesterol synthesis. It is an autosomal recessive, multiple malformation syndrome caused by a mutation in the enzyme 7-Dehydrocholesterol reductase encoded by the DHCR7 gene. It causes a broad spectrum of effects, ranging from mild intellectual disability and behavioural problems to lethal malformations.
Signs and symptoms
SLOS can present itself differently in different cases, depending on the severity of the mutation and other factors. Originally, SLOS patients were classified into two categories (classic and severe) based on physical and mental characteristics, alongside other clinical features. Since the discovery of the specific biochemical defect responsible for SLOS, patients are given a severity score based on their levels of cerebral, ocular, oral, and genital defects. It is then used to classify patients as having mild, classical, or severe SLOS.
Physical characteristics
The most common facial features of SLOS include microcephaly, bitemporal narrowing (reduced distance between temples), ptosis, a short and upturned nose, micrognathia, epicanthal folds, and capillary hemangioma of the nose. Other physical characteristics include:
low-set and posteriorly rotated ears
high-arched, narrow, hard palate
cleft lip/palate
agenesis or hypoplasia of the corpus callosum
cerebellar hypoplasia
increased ventricular size
decreased frontal lobe size
polydactyly of hands or feet
short, proximally placed thumb
other finger malformations
syndactyly of second and third toes
ambiguous or female-like male genitalia
congenital heart defects
renal, pulmonary, liver and eye abnormalities
Behavioural characteristics
Certain behaviours and attributes are commonly seen among patients with SLOS. They may have low normal intelligence, and react negatively or with hypersensitivity to different sensory stimuli. This is particularly true for certain auditory and visual stimuli. Many patients show aggressiveness and self-injurious behaviours, and sleep disturbances are common.
“Smith–Lemli–Opitz syndrome” enters the record as an inborn error of cholesterol synthesis, caused by a mutation in the enzyme 7-Dehydrocholesterol reductase. Crown Archives preserves that source wording while asking what Smith, Lemli and Opitz can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 10, 2026. The linked authority identifier is Q998273. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Smith–Lemli–Opitz syndrome” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.