Smith-Lemli-Opitz syndrome

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Smith-Lemli-Opitz syndrome Classification and external resources
ICD-10	Q87.1
OMIM	270400
DiseasesDB	12223
eMedicine	ped/2117
MeSH	C16.131.077.860

Smith-Lemli-Opitz syndrome (also SLOS or 7-dehydrocholesterol reductase deficiency) is a 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).

Incidence/prevalence

Smith-Lemli-Opitz syndrome affects an estimated 1 in 20,000 to 40,000 births. This condition is most common in Caucasians of European ancestry. It is very rare among African and Asian populations. This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered.

Genetics

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 is 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 is not 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.^[1]

Notable cases

According to CNN, 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.^[1]

References

Template:GHR

External links

• Richard I. Kelley on SLOS
• Overview of condition at NLM Genetics Home Reference

v • d • e Phakomatoses and other congenital malformations not elsewhere classified (Q85-Q89, 759)
Phakomatoses	Abdallat Davis Farrage syndrome - Ataxia telangiectasia - Incontinentia pigmenti - Neurofibromatosis (type I, type II) - Peutz-Jeghers syndrome - Sturge-Weber syndrome - Tuberous sclerosis - Von Hippel-Lindau disease
Due to known exogenous causes	Fetal alcohol syndrome - Phocomelia (via Thalidomide)
Affecting multiple systems	facial (Mobius syndrome, Goldenhar syndrome, Cyclopia, Apert syndrome) short stature (Aarskog-Scott syndrome, Cockayne syndrome, Cornelia de Lange Syndrome, Dubowitz syndrome, Noonan syndrome, Robinow syndrome, Silver-Russell dwarfism, Seckel syndrome, Smith-Lemli-Opitz syndrome) limbs (Adducted thumb syndrome, Holt-Oram syndrome, Klippel-Trenaunay-Weber syndrome, Nail-patella syndrome, Rubinstein-Taybi syndrome, Sirenomelia, VACTERL association) overgrowth (Beckwith-Wiedemann syndrome, Sotos syndrome, Weaver syndrome) combined/other Ablepharon macrostomia syndrome - Alport syndrome - Bardet-Biedl syndrome - Branchio-oto-renal syndrome - Donohue syndrome - Fraser syndrome - Keutel syndrome - Marfan syndrome - Timothy syndrome - Urban-Rogers-Meyer syndrome - Vici syndrome - Yunis-Varon syndrome - Zellweger syndrome - Zimmerman-Laband syndrome - Zori Stalker Williams syndrome
Other	spleen: Asplenia - Splenomegaly endocrine glands: Persistent thyroglossal duct - Thyroglossal cyst Conjoined twins - Cowden syndrome - Hamartoma - Impossible syndrome - Situs inversus

de:Smith-Lemli-Opitz-Syndrom

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .