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.
A 2014 review found that "even in a theoretical case of binge drinking, the children would not be subjected to clinically relevant amounts of alcohol [through breastmilk]", and would have no adverse effects on children as long as drinking is "occasional".If the mother consumes too much caffeine, it can cause irritability, sleeplessness, nervousness and increased feeding in the breastfed infant. Moderate use (one to two cups per day of coffee, tea, or cola) usually produces no effect. Breastfeeding mothers are advised to restrict or avoid caffeine if her baby reacts negatively to it. Cigarette smoking is thought to increase the effects of caffeine in the baby. Cannabis
Cannabis is listed by the American Association of Pediatrics as a compound that transfers into human breast milk. Research demonstrated that certain compounds in marijuana have a very long half-life. Diet
An exclusively breastfed baby depends on breast milk completely so it is important for the mother to maintain a healthy lifestyle, and especially a good diet. Consumption of 1500–1800 calories per day could coincide with a weight loss of 450 grams (one pound) per week. While mothers in famine conditions can produce milk with highly nutritional content, a malnourished mother may produce milk with decreased levels of several micronutrients such as iron, zinc, and vitamin B12. She may also have a lower supply than well-fed mothers. There are no foods that are absolutely contraindicated during breastfeeding, but a baby may show sensitivity to particular foods that the mother eats.