Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Smith-Lemli-Opitz syndrome (SLOS) is an inborn disorder of sterol metabolism with characteristic congenital malformations and dysmorphias. All patients suffer from mental retardation. Here we identify the SLOS gene as a Delta7-sterol reductase (DHCR7, EC 1.3.1. 21) required for the de novo biosynthesis of cholesterol. The human and murine genes were characterized and assigned to syntenic regions on chromosomes 11q13 and 7F5 by fluorescense in situ hybridization. Among the mutations found in patients with the SLOS, are missense (P51S, T93M, L99P, L157P, A247V, V326L, R352W, C380S, R404C, and G410S), nonsense (W151X), and splice site (IVS8-1G>C) mutations as well as an out of frame deletion (720-735 del). The missense mutations L99P, V326L, R352W, R404C, and G410S reduced heterologous protein expression by >90%. Our results strongly suggest that defects in the DHCR7 gene cause the SLOS.
 ...
PMID:Mutations in the Delta7-sterol reductase gene in patients with the Smith-Lemli-Opitz syndrome. 965 61

A case of severe photosensitivity in a girl with the Smith-Lemli-Opitz syndrome is reported. Children with this recessively inherited metabolic disorder of cholesterol metabolism present with a variety of congenital abnormalities of the nervous system and internal organs in association with varying degrees of mental retardation. Photosensitivity is a feature which has previously only briefly been mentioned in the literature in association with this syndrome. However, more recently, it has become apparent that photosensitivity is not uncommon among children with the Smith-Lemli-Opitz syndrome, although the nature of the photosensitivity in these patients has remained undefined. Our patient has suffered from sunlight intolerance since early infancy, with redness and pruritus of sun-exposed skin developing within minutes of sun exposure. Monochromator ultraviolet (UV) radiation and visible light testing revealed an immediate and persistent reaction to low-dose UVA at 350 nm, and an abnormal erythemal response to visible light at 400 nm.
 ...
PMID:Photosensitivity associated with the Smith-Lemli-Opitz syndrome. 966 40

Two brothers are presented who were previously diagnosed to have atypical Smith-Lemli-Opitz syndrome. On repeated examinations, however, the facial anomalies of the patients suggested that they would have rather alpha-thalassaemia/mental retardation syndrome. The presence of hemoglobin H inclusions in the peripheral red blood cell supported the clinical suspicion. The search for hemoglobin H inclusions should be considered as a screening test when evaluating mentally retarded boys.
 ...
PMID:[Alpha thalassemia/metal retardation syndrome--a new X-chromosome linked recessive genetically inherited symptom complex]. 967 15

Smith-Lemli-Opitz syndrome is a frequently occurring autosomal recessive developmental disorder characterized by facial dysmorphisms, mental retardation, and multiple congenital anomalies. Biochemically, the disorder is caused by deficient activity of 7-dehydrocholesterol reductase, which catalyzes the final step in the cholesterol-biosynthesis pathway-that is, the reduction of the Delta7 double bond of 7-dehydrocholesterol to produce cholesterol. We identified a partial transcript coding for human 7-dehydrocholesterol reductase by searching the database of expressed sequence tags with the amino acid sequence for the Arabidopsis thaliana sterol Delta7-reductase and isolated the remaining 5' sequence by the "rapid amplification of cDNA ends" method, or 5'-RACE. The cDNA has an open reading frame of 1,425 bp coding for a polypeptide of 475 amino acids with a calculated molecular weight of 54.5 kD. Heterologous expression of the cDNA in the yeast Saccharomyces cerevisiae confirmed that it codes for 7-dehydrocholesterol reductase. Chromosomal mapping experiments localized the gene to chromosome 11q13. Sequence analysis of fibroblast 7-dehydrocholesterol reductase cDNA from three patients with Smith-Lemli-Opitz syndrome revealed distinct mutations, including a 134-bp insertion and three different point mutations, each of which was heterozygous in cDNA from the respective parents. Our data demonstrate that Smith-Lemli-Opitz syndrome is caused by mutations in the gene coding for 7-dehydrocholesterol reductase.
 ...
PMID:Smith-Lemli-Opitz syndrome is caused by mutations in the 7-dehydrocholesterol reductase gene. 968 18

The Smith-Lemli-Opitz syndrome, characterized by limb, face and organ abnormalities, and mental retardation, is caused by an inherited block in the step of cholesterol biosynthesis in which the delta 7 double bond of 7-dehydrocholesterol is reduced. It is diagnosed by the presence of markedly elevated levels of 7-dehydrocholesterol and 8-dehydrocholesterol in plasma and tissue. We measured amniotic fluid sterols in 15 pregnancies in 13 women who had previously carried an affected fetus. Cholesterol, 7-dehydrocholesterol and 8-dehydrocholesterol concentrations averaged 18 +/- 3, 9.8 +/- 2.9 and 5.0 +/- 1.7 micrograms/ml, respectively, in seven pregnancies with an affected fetus or child. In contrast, these levels were 19 +/- 3, 0.05 +/- 0.01 and < 0.005 micrograms/ml, respectively, in eight increased-risk pregnancies with normal outcomes and 16 +/- 2, 0.07 +/- 0.01 and < 0.005 micrograms/ml in normal controls. 7-dehydrocholesterol concentrations, 2.2-26 and 0.05-0.10 micrograms/ml in pregnancies with an affected and unaffected fetus, respectively, did not overlap. Thus, abnormally elevated amniotic fluid dehydrocholesterol concentrations are an accurate predictor of fetal Smith-Lemli-Opitz syndrome. A false-positive or a false-negative result is highly unlikely.
 ...
PMID:Fetal Smith-Lemli-Opitz syndrome can be detected accurately and reliably by measuring amniotic fluid dehydrocholesterols. 970 45

Smith-Lemli-Opitz syndrome (SLO) is caused by inherited enzymatic deficiency of 7-dehydrocholesterol-delta7-reductase and resultant cholesterol deficiency. It comprises a characteristic combination of facial features, malformations, and mental retardation. We report on three related patients (two brothers and their first cousin) with mental retardation and minimal physical signs in whom the diagnosis of SLO was delayed for a number of years. The presence of a third-degree relative in the absence of consanguinity in this family supports the proposed high population carrier frequency. Our report suggests that cases of mild SLO remain undiagnosed and untreated, and that awareness of this common cause of mental retardation is low.
 ...
PMID:Smith-Lemli-Opitz syndrome: phenotypic extreme with minimal clinical findings. 971 7

Smith-Lemli-Opitz (SLO) syndrome is an autosomal recessive disorder comprised of recognizable facial abnormalities, growth retardation, and multiple congenital anomalies, commonly involving genitalia, second and third toe syndactyly, and cleft palate. The condition is associated with hypocholesterolemia and elevated levels of 7-dehydrocholesterol (7DHC) resulting from deficient activity of the enzyme 7-dehydrocholesterol reductase. The clinical spectrum of SLO ranges from individuals with mental retardation and minor anomalies to those with major structural defects and early or even prenatal lethality. Low maternal serum unconjugated estriol (uE3) levels and a variety of fetal ultrasound anomalies have been identified in affected pregnancies, and prenatal diagnosis is possible by measurement of amniotic fluid 7DHC levels in pregnancies known to be at risk because of a previously affected child. We report on a pregnancy with low maternal uE3 level, abnormal antenatal ultrasound findings including limb deformities, ventriculomegaly, and hydrops fetalis, and a normal 46,XY karyotype. The infant died at birth. At autopsy the infant had hydrops, unusual face, cleft palate, genital abnormalities, Dandy-Walker malformation, and absence of toe syndactyly. Tests performed on cultured skin fibroblasts showed elevated levels of 7DHC and abnormalities of cholesterol biosynthesis characteristic of the metabolic defect that causes SLO. The atypical findings of hydrops, uncharacteristic facial appearance, and absence of toe syndactyly in this case additionally illustrates the wide phenotypic spectrum of SLO and the need for a high index of suspicion for a disorder with great clinical variability. Identification of another affected pregnancy with a low maternal uE3 level and abnormal fetal ultrasound findings in the presence of a normal karyotype lends additional support for consideration of prenatal biochemical testing for SLO in pregnancies with these findings, including pregnancies not previously known to be at risk.
 ...
PMID:Atypical case of Smith-Lemli-Opitz syndrome: implications for diagnosis. 985 57

The RSH/Smith-Lemli-Opitz syndrome (RSH/SLOS) is a relatively common, autosomal recessive malformation syndrome comprising distinctive facial, limb and genital anomalies, and mental retardation. Most patients with a clinical diagnosis of RSH/SLOS have a defect of cholesterol biosynthesis at the level of 3beta-hydroxysteroid-delta7-reductase, resulting in a decreased level of cholesterol and an increased level of 7-dehydrocholesterol (7DHC) in body fluids and tissues. We report on our experience with the prenatal diagnosis of RSH/SLOS by quantitative sterol chromatography in amniotic fluid (AF) and chorionic villus (CV). Of 76 AF and nine CV samples analyzed for various indications, 20 were diagnostic of RSH/SLOS based on an increased level of 7DHC in the fluid or tissue. Of 39 fetuses at a 25% risk for RSH/SLOS, 10(25.6%) were affected. Twenty-nine pregnancies not known to be at risk for RSH/SLOS were studied because of either a fetal abnormality characteristic of RSH/SLOS detected by ultrasound, a low maternal serum uE3 level (MSuE3), or both. None of the pregnancies tested, because of a low MSuE3 but lacking a sonographic abnormality characteristic of RSH/SLOS, was affected. However, three of four pregnancies with a low MSuE3 and an RSH/SLOS-type fetal abnormality were positive. RSH/ SLOS was diagnosed in two additional pregnancies on which MSuE3 data were not available but in which fetal anomalies were identified. Of these five RSH/SLOS fetuses identified in pregnancies not otherwise at risk for RSH/SLOS, the presenting sonographic anomaly was either polydactyly, ambiguous genitalia, or both. Evaluation of the biochemical parameters and clinical severity of RSH/SLOS showed that there was an inverse correlation between clinical severity and both the level of AF 7DHC and the level of MSuE3. Based on these earlier and more extensive studies, we conclude that accurate prenatal diagnosis of RSH/ SLOS is possible by sterol analysis of AF and, most likely, CV specimens as well. Furthermore, our findings suggest that MSuE3 levels in combination with sonography may provide useful diagnostic and prognostic information in the absence of a family history of RSH/SLOS.
 ...
PMID:Prenatal diagnosis of the RSH/Smith-Lemli-Opitz syndrome. 1006 7

Smith-Lemli-Opitz (SLO or RSH) syndrome is characterized by multiple congenital anomalies, mental retardation, and defective growth; it results from an inherited defect in the biosynthesis of cholesterol. Patients have elevated plasma concentrations of 7-dehydrocholesterol, the immediate biosynthetic precursor of cholesterol and most also have low circulating levels of cholesterol. To understand better the biochemical basis of clinical variability, we evaluated cholesterol biosynthesis in lymphoblasts from 3 unrelated SLOS patients with distinct phenotypes. One patient has "type I SLOS", the second has the more severe "type II SLOS" and the third is classified as atypical and had been postulated to have a defect in sterol transport. The lymphoblasts of each patient show normal subcellular localization of cholesterol and 7-dehydrocholesterol by gradient fractionation. Biochemical differences in the ability of the lymphoblasts to convert 7-dehydrocholesterol to cholesterol are described and correspond to the severity of disease (type II > type I > atypical). Recently, the gene responsible for most SLOS cases (DHCR7) was mapped to chromosome 11 and mutations in DHCR7 were found in each of these patients. The biochemical differences described here likely result from the different mutations observed in DHCR7.
 ...
PMID:Biochemical variants of Smith-Lemli-Opitz syndrome. 1040 55

Smith-Lemli-Opitz syndrome, a syndrome of multiple malformations and mental retardation that for years was relegated to the atlases of genetic esoterica, was recently found to be a relatively common inborn error of metabolism. The underlying defect is absent or deficient activity of 7-dehydrocholesterol- delta 7-reductase, the enzyme catalysing the final step of cholesterol synthesis. The discovery of the biochemical defect causing Smith-Lemli-Opitz syndrome has resulted in the development of a diagnostic test and a potentially beneficial treatment (dietary cholesterol supplementation). Infants and young children with the syndrome have shown marked improvement in growth, behaviour and general health after receiving cholesterol therapy; older children and adults have shown some improvement in development and intellectual functioning. Despite the excitement these developments have elicited among geneticists and biochemists, this syndrome remains relatively unknown to many primary care physicians. Increased awareness of Smith-Lemli-Opitz syndrome is needed to identify affected patients so that they and their families can benefit from appropriate treatment and genetic counselling.
 ...
PMID:Smith-Lemli-Opitz syndrome: a treatable inherited error of metabolism causing mental retardation. 1043 27


<< Previous 1 2 3 4 5 6 7 8 Next >>