Everything about Smith-lemli-opitz Syndrome totally explained
Smith-Lemli-Opitz syndrome (also
SLOS, or
7-dehydrocholesterol reductase deficiency) is a
metabolic and developmental disorder that affects many parts of the body.
Presentation
This condition is characterized by distinctive facial features, small head size (
microcephaly),
mental retardation or learning disabilities, and behavioral problems. Malformations of the
heart,
lungs,
kidneys,
gastrointestinal tract, and
genitalia are also common. Infants with Smith-Lemli-Opitz syndrome have weak muscle tone (
hypotonia), experience feeding difficulties, and tend to grow more slowly than other infants. Most affected individuals have fused second and third toes (
syndactyly), and some have extra fingers or toes (
polydactyly).
Genetic prevalence
Smith-Lemli-Opitz syndrome affects an estimated 1 in 20,000 to 40,000 births. It is most common in
Caucasians of European ancestry, but very rare among African and Asian populations.
This disorder is inherited in an
autosomal recessive pattern, which means two copies of the
gene in must be inherited to have the disorder.
Mutations in the
DHCR7 gene cause Smith-Lemli-Opitz syndrome. The
DHCR7 gene makes an
enzyme called
7-dehydrocholesterol reductase. This enzyme is responsible for the final step in the production of
cholesterol. Cholesterol is an essential nutrient that's necessary for normal
embryonic development. Cholesterol is also a structural component of
cell membranes and the protective substance covering
nerve cells (
myelin). Additionally, cholesterol plays an important role in the production of certain
hormones and digestive acids.
Mutations in the
DHCR7 gene reduce or eliminate the activity of
7-dehydrocholesterol reductase, preventing cells from producing enough cholesterol. A lack of this enzyme also allows potentially toxic byproducts of cholesterol production to build up in the blood and other tissues. The combination of low cholesterol levels and an accumulation of other substances likely disrupts the growth and development of many body systems. It isn't known, however, how this disturbance in cholesterol production leads to the specific features of Smith-Lemli-Opitz syndrome.
Associated conditions
A 2006 study of 14 children with Smith-Lemli-Opitz syndrome reported that most children with SLOS have an
autism spectrum disorder. SLOS appears to have the most consistent relationship with
autism of any single-gene disorder.
Notable cases
On July 24th, 2007 a jury awarded a Florida couple, Daniel and Amara Estrada, whose sons are afflicted with Smith-Lemli-Opitz syndrome, 21 million dollars in damages. The Estradas claimed that Dr. Boris Kousseff failed to diagnose their first son's genetic disorder, leading to them having another son with the disorder.
Further Information
Get more info on 'Smith-lemli-opitz Syndrome'.
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