Smith-Lemli-Opitz syndrome (SLO syndrome) is a genetic disease that affects about 1 child every 20,000 / 40,000. Transmission is autosomal recessive, so it has a 25% recurrence risk. Most cases are evident from birth, but the diagnosis of some mild forms can only come into adulthood.
The most characteristic symptoms of SLO syndrome are microcephaly, facial dysmorphism, mental retardation, behavioral disorders. The latter include mainly autism spectrum behaviors, hyperactivity and self-harm. Some subjects also show ocular disorders ranging from cataracts to retinal degeneration, resulting in blindness. Others show congenital cardiopathies and gastrointestinal abnormalities.
The cause of Smith-Lempli-Opitz syndrome is a metabolic disease caused by a mutation of the DHCR7 gene. This causes problems in the synthesis of cholesterol, lowering its levels excessively. The absence of cholesterol therefore translates into the physical and neurological deficits mentioned above.
The diagnosis of SLO can also occur in the prenatal stage. Prenatal screening such as fetal ultrasound, amniocentesis and villocentesis are able to tell whether the fetus is ill or not. In the case of a positive diagnosis, only symptomatic therapies are available today. It proceeds then integrating the missing cholesterol and treating any malformations. In severe cases, these lead to an early death.