Smith-Lemli-Opitz Syndrome Research Articles

Elevated cerebrospinal fluid glial fibrillary acidic protein levels in Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is a rare, multiple malformation/intellectual disability disorder caused by pathogenic variants of DHCR7. DHCR7 catalyzes the reduction of 7-dehydrocholesterol (7DHC) to cholesterol in the final step of cholesterol biosynthesis. This results in accumulation of 7DHC and a cholesterol deficiency. Although the biochemical defect is well delineated and multiple mechanisms underlying developmental defects have been explored, the post developmental neuropathological consequences of altered central nervous system sterol composition have not been studied. Preclinical studies suggest that astroglial activation may occur in SLOS. To determine if astroglial activation is present in individuals with SLOS, we quantified cerebrospinal fluid (CSF) glial fibrillary acidic protein using a Quanterix Simoa® GFAP Discovery Kit for SR-X™. Relative to an age-appropriate comparison group, we found that CSF GFAP levels were elevated 3.9-fold in SLOS (3980 ± 3732 versus 1010 ± 577 pg/ml, p = 0.0184). Simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, has previously been shown to increase expression of hypomorphic DHCR7 alleles and in a placebo-controlled trial improved serum sterol levels and decreased irritability. Using archived CSF samples from that prior study, we observed a significant decrease (p = 0.0119) in CSF GFAP levels in response to treatment with simvastatin. Although further work needs to be done to understand the potential contribution of neuroinflammation to SLOS neuropathology and cognitive dysfunction, these data confirm astroglial activation in SLOS and suggest that CSF GFAP may be a useful biomarker to monitor therapeutic responses.

Alpha-Thalassemia X-Linked Intellectual Disability Syndrome in a Boy with a Strong Family History of Smith–Lemli–Opitz's Syndrome

AbstractAlpha-thalassemia X-linked intellectual disability (ATRX) syndrome is a rare disorder characterized by facial dysmorphism, genitourinary tract abnormalities, alpha-thalassemia, and cognitive impairment. Patients present in early infancy with hypotonia, microcephaly, failure to thrive, and delayed milestones. We report a boy with strong family history of the Smith–Lemli–Opitz's syndrome (SLOS) phenotype. All affected family members displayed facial features and presentation identical to those of our patient. None had hypocholesterolemia. All affected family members were boys and have died. Molecular genetic testing in our patient revealed a likely pathogenic mutation in the X-linked recessive ATRX gene. We conclude that SLOS and ATRX syndrome are uncommon disorders sharing similar manifestations. Awareness of such similarity should prompt physicians to explore the possibility of ATRX syndrome in relatives of patients with unproven SLOS.

Cholesterol regulates insulin-induced mTORC1 signaling.

The rapid activation of the crucial kinase mechanistic target of rapamycin complex-1 (mTORC1) by insulin is key to cell growth in mammals, but the regulatory factors remain unclear. Here, we demonstrate that cholesterol plays a crucial role in the regulation of insulin-stimulated mTORC1 signaling. The rapid progression of insulin-induced mTORC1 signaling declines in sterol-depleted cells and restores in cholesterol-repleted cells. In insulin-stimulated cells, cholesterol promotes recruitment of mTORC1 onto lysosomes without affecting insulin-induced dissociation of the TSC complex from lysosomes, thereby enabling complete activation of mTORC1. We also show that under prolonged starvation conditions, cholesterol coordinates with autophagy to support mTORC1 reactivation on lysosomes thereby restoring insulin-responsive mTORC1 signaling. Furthermore, we identify that fibroblasts from individuals with Smith-Lemli-Opitz Syndrome (SLOS) and model HeLa-SLOS cells, which are deficient in cholesterol biosynthesis, exhibit defects in the insulin-mTORC1 growth axis. These defects are rescued by supplementation of exogenous cholesterol or by expression of constitutively active Rag GTPase, a downstream activator of mTORC1. Overall, our findings propose novel signal integration mechanisms to achieve spatial and temporal control of mTORC1-dependent growth signaling and their aberrations in disease.

Abstract 17196: Genetic and Acquired DHCR7 Deficiency Upregulates 7β-hydroxycholesterol to Drive Endothelial Apoptosis and Pulmonary Hypertension

Introduction: Pulmonary hypertension (PH) is a fatal disease without a cure, in which endothelial dysfunction drives pathologic remodeling of the pulmonary vasculature. Individuals with Smith-Lemli-Opitz syndrome (SLOS) develop PH, but the underlying mechanisms remain undefined. SLOS is an autosomal recessive disorder of cholesterol synthesis, resulting from loss-of-function mutations in 7-dehydrocholesterol reductase (DHCR7)-the terminal enzyme in the de novo synthesis of cholesterol- that leads to accumulation of 7-dehydrocholesterol (7-DHC) and cytotoxic oxysterol species. The role of DHCR7 in PH, however, is unknown. Hypothesis: Elevated cytotoxic oxysterols resulting from genetic or acquired DHCR7 deficiency promotes endothelial dysfunction and the development of PH. Methods & Results: DHCR7 mRNA and protein expression was decreased in pulmonary artery endothelial cells (ECs) in cellular (P=0.0089), rodent, and human PH models, mirroring DHCR7 reduction in SLOS. Both genetic loss of DHCR7 and hypoxia promoted a global shutdown of de novo cholesterol synthesis, resulting in an accumulation of cholesterol intermediates and increased derivative oxysterols. Specifically, 7β-hydroxycholesterol (7β-HC) was elevated in DHCR7-deficient ECs (P<0.0001), and 7β-HC drove endothelial apoptosis (P<0.0001) via downregulation of insulin-like growth factor 1 (IGF1) in ECs (fold change=0.101 ± 0.034, FDR=6.65E-11). Conversely, overexpression of DHCR7 upregulated IGF1 expression (P<0.0007), and IGF1 delivery reversed apoptosis (P<0.0001). Correspondingly, ECs derived from SLOS patient stem cells with DHCR7 mutations (p.T93M/c.964-1G>C) exhibited IGF1-dependent apoptosis. Finally, EC-specific DHCR7 deletion in chronically hypoxic mice induced more severe PH in vivo (right ventricular systolic pressure 36.4 mmHg vs. 30.8 mmHg, P<0.0130). Conclusions: Resulting either from hypoxic or genetic causes, DHCR7 deficiency promoted EC apoptosis and PH via 7β-HC accumulation and subsequent IGF1 downregulation. Our work is the first to define an oxysterol-dependent mechanism underlying the link between genetic and acquired DHCR7 deficiency and PH.

Prenatal diagnosis of lanosterol synthase deficiency: Fetal ultrasound findings as a window on family genetics

Cholesterol is essential in the brain from the earliest stages of embryonic development. Disruption of cholesterol synthesis pathways that leads to cholesterol deficiency underlies a few syndromes, including desmosterolosis and Smith–Lemli–Opitz syndrome. In both syndromes, brain anomalies can occur. The LSS gene encodes lanosterol synthase (LSS), an important enzyme in the cholesterol biosynthesis pathway. Biallelic pathogenic variants in this gene cause alopecia–intellectual disability type 4 syndrome (APMR4, MIM 618840), a rare autosomal recessive disorder. Here, we describe two new LSS variants (c.1016C > T; p. Ser339Leu and c.1522G > C; p. Gly508Arg) found in a compound heterozygous fetus diagnosed prenatally with brain abnormalities by ultrasound scanning. Two of his siblings from the same parents also harbored these variants. Both siblings had alopecia, mild intellectual disability, autism spectrum disorder, and cataracts. To the best of our knowledge, this case represents the first prenatal diagnosis of APMR4 first suspected by ultrasound. In addition, the phenotypic features of the siblings are extensive compared with those described in previous reports and include abnormal corpus callosum, cataracts, alopecia, and developmental delay.

Effect of maternal polycystic ovary syndrome (PCOS) on screening of aneuploidy in the first and second trimesters

BackgroundPolycystic ovary syndrome (PCOS) is characterized by insulin resistance and hormonal disorder in women. This study aimed to assess the effect of maternal PCOS on screening of aneuploidy in the first and second-trimesters.MethodsThis case-control study was conducted in Arash Hospital and Nilou Laboratory in 2017–2018. The screening test was conducted on 90 PCOS and 90 healthy mothers. Finally, the first and second-trimester screening was compared between the two groups using Chi-square, Mann-Whitney’s U and students T tests and regression model by SPSS 21. P < 0.05 was considered as statistically significant.ResultsFree Beta-Human Chorionic Gonadotropin (Free-β-HCG) (P = 0.04), inhibin-A (P = 0.001) and Alpha Fetoprotein (AFP) (P = 0.02) levels were higher in the PCOS women comparing to the healthy women but there was no significant difference between the mean of HCG, Plasma Protein A (PAPP-A), and Unconjugated Estriol (UE3) between the two groups. Pre-eclampsia (P < 0.001) and trisomy 18 risks in quad screening were higher in the PCOS women (P = 0.002) than the control group; however, trisomy 13, trisomy 18 and trisomy 21 risks, Smith-Lemli-Opitz Syndrome (SLOS) and Neural Tube Defect (NTD) risks were not different between the two groups. The logistic regression model showed that the first- and second-trimester screening of aneuploidywas related to PCOS.ConclusionsThere was a significant difference in the mean of free-β-HCG, inhibin-A, AFP level, and the risks of pre-eclampsia, SLOS and trisomy 18 between the two groups but no significant association was found in the mean of HCG, PAPP-A, UE3, NTD and other aneuploidies between the two groups. PCOS may affect the first- and second-trimester screening tests and pregnancy health. It may also require correction in the calculation of risks related to the first- and second-trimester screening for aneuploidy.

Sterol physical properties and relationships to endo-/exocytosis.

Multiple diseases arise from sterol homeostasis disruption and are characterized at the molecular level by depletion or accumulation of sterol species. One such disease is Smith-Lemli-Opitz syndrome (SLOS) that results from genetic mutations in a particular cholesterol synthesis enzyme, which leads to depletion of cholesterol and accumulation of 7-dehydrocholesterol (7DHC). Recent in vivo work demonstrated that depleting/enriching specific sterol species modulated clathrin-mediated endocytosis (CME) that might contribute to the cellular phenotypes observed in disease states. The CME results were explained by softening mechanisms involving sterol lateral redistribution, but it remains a question as to why this occurs. Here, we take the outlook that differences in Gaussian curvature modulus and local lipid composition destabilize narrow necks in fission, reducing the membrane's apparent rigidity. Using membrane fluctuation analysis, we quantify sterol physical properties that partially define the fusion/fission energetic pathway, for example: the compressibility modulus, bending modulus, leaflet neutral surface, leaflet spontaneous curvature, bilayer thickness preference, and thickness contribution to the Gaussian modulus. Using these quantities, we make predictions on where sterol species will redistribute on strongly curved membranes. Finally, we use all-atom simulations of strongly curved fusion pore and hemifusion diaphragm geometries to quantify the sterol redistribution and compare to hypotheses. Comparing cholesterol and 7DHC physical properties, for example, the key statistically significant quantity is the thickness contribution to the Gaussian modulus, and we predicted that 7DHC would be less excluded from the fusion pore than cholesterol. All-atom molecular dynamics simulations of the fusion pore confirmed this hypothesis. The result correlates to in vivo experiments that showed reduced CME with 7DHC compared to cholesterol (p < 0.10). Other tests are ongoing.

Smith-Lemli-Opitz syndrome: A pathophysiological manifestation of the Bloch hypothesis.

The biosynthesis of cholesterol, an essential component of higher eukaryotic membranes, was worked out by Konrad Bloch (and Feodor Lynen) in the 1960s and they received the Nobel Prize around that time in recognition of their pioneering contributions. An elegant consequence of this was a hypothesis proposed by Konrad Bloch (the Bloch hypothesis) which suggests that each subsequent intermediate in the cholesterol biosynthesis pathway is superior in supporting membrane function in higher eukaryotes relative to its precursor. In this review, we discuss an autosomal recessive metabolic disorder, known as Smith-Lemli-Opitz syndrome (SLOS), associated with a defect in the Kandutsch-Russell pathway of cholesterol biosynthesis that results in accumulation of the immediate precursor of cholesterol in its biosynthetic pathway (7-dehydrocholesterol) and an altered cholesterol to total sterol ratio. Patients suffering from SLOS have several developmental, behavioral and cognitive abnormalities for which no drug is available yet. We characterize SLOS as a manifestation of the Bloch hypothesis and review its molecular etiology and current treatment. We further discuss defective Hedgehog signaling in SLOS and focus on the role of the serotonin1A receptor, a representative neurotransmitter receptor belonging to the GPCR family, in SLOS. Notably, ligand binding activity and cellular signaling of serotonin1A receptors are impaired in SLOS-like condition. Importantly, cellular localization and intracellular trafficking of the serotonin1A receptor (which constitute an important determinant of a GPCR cellular function) are compromised in SLOS. We highlight some of the recent developments and emerging concepts in SLOS pathobiology and suggest that novel therapies based on trafficking defects of target receptors could provide new insight into treatment of SLOS.

Sterol dysregulation in Smith-Lemli-Opitz syndrome causes astrocyte immune reactivity through microglia crosstalk.

Owing to the need for de novo cholesterol synthesis and cholesterol-enriched structures within the nervous system, cholesterol homeostasis is critical to neurodevelopment. Diseases caused by genetic disruption of cholesterol biosynthesis, such as Smith-Lemli-Opitz syndrome, which is caused by mutations in 7-dehydrocholesterol reductase (DHCR7), frequently result in broad neurological deficits. Although astrocytes regulate multiple neural processes ranging from cell migration to network-level communication, immunological activation of astrocytes is a hallmark pathology in many diseases. However, the impact of DHCR7 on astrocyte function and immune activation remains unknown. We demonstrate that astrocytes from Dhcr7 mutant mice display hallmark signs of reactivity, including increased expression of glial fibrillary acidic protein (GFAP) and cellular hypertrophy. Transcript analyses demonstrate extensive Dhcr7 astrocyte immune activation, hyper-responsiveness to glutamate stimulation and altered calcium flux. We further determine that the impacts of Dhcr7 are not astrocyte intrinsic but result from non-cell-autonomous effects of microglia. Our data suggest that astrocyte-microglia crosstalk likely contributes to the neurological phenotypes observed in disorders of cholesterol biosynthesis. Additionally, these data further elucidate a role for cholesterol metabolism within the astrocyte-microglia immune axis, with possible implications in other neurological diseases.

Statins for Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a multiple congenital malformations syndrome caused by defective cholesterol biosynthesis. Affected individuals show cholesterol deficiency and accumulation of various precursor molecules, mainly 7-dehydrocholesterol and 8-dehydrocholesterol. There is currently no cure for SLOS, with cholesterol supplementation being primarily a biochemical therapy of limited evidence. However, several anecdotal reports and preclinical studies have highlighted statins as a potential therapy for SLOS. To evaluate the effects of statins, either alone or in combination with other non-statin therapies (e.g. cholesterol, bile acid, or vitamin co-supplementation), compared to cholesterol supplementation alone or in combination with other non-statin therapies (e.g. bile acid or vitamin supplementation) on several important outcomes including overall survival, neurobehavioral features, and adverse effects in individuals with SLOS. We searched CENTRAL, MEDLINE, Embase, five other databases and three trials registers on 15 February 2022, together with reference checking, citation searching and contact with study authors to identify additional studies. Randomized controlled trials (RCTs) and quasi-RCTs with parallel or cross-over designs, and non-randomized studies of interventions (NRSIs) including non-randomized trials, cohort studies, and controlled before-and-after studies, were eligible for inclusion in this review if they met our prespecified inclusion criteria, i.e. involved human participants with biochemically or genetically diagnosed SLOS receiving statin therapy or cholesterol supplementation, or both. Two authors screened titles and abstracts and subsequently full-texts for all potentially-relevant references. Both authors independently extracted relevant data from included studies and assessed the risks of bias. We analyzed the data extracted from the included NRSIs and cohort studies separately from the data extracted from the single included RCT. We used a random-effects model to account for the inherent heterogeneity and methodological variation between these different study designs. We used GRADE to assess the certainty of evidence. We included six studies (61 participants with SLOS); one RCT (N = 18), three prospective NRSIs (N = 20), and two retrospective NRSIs (N = 22). Five studies included only children, and two limited their participant inclusion by disease severity. Overall, there were nearly twice as many males as females. All six studies compared add-on statin therapy to cholesterol supplementation alone. However, the dosages, formulations, and durations of treatment were highly variable across studies. We judged the RCT as having a high risk of bias due to missing data and selective reporting. All included NRSIs had a serious or critical overall risk of bias assessed by the Risk Of Bias In Non-randomized Studies of Interventions tool (ROBINS-I). None of the included studies evaluated survival or reported quality of life (QoL). Only the included RCT formally assessed changes in the neurobehavioral manifestations of SLOS, and we are uncertain whether statin therapy improves this outcome (very low-certainty evidence). We are also uncertain whether the adverse events reported in the RCT were statin-related (very low-certainty evidence). In contrast, the adverse events reported in the NRSIs seem to be possibly due to statin therapy (risk ratio 13.00, 95% confidence interval 1.85 to 91.49; P = 0.01; low-certainty evidence), with only one of the NRSIs retrospectively mentioning changes in the irritability of two of their participants. We are uncertain whether statins affect growth based on the RCT or NRSI results (very low-certainty evidence). The RCT showed that statins may make little or no difference to plasma biomarker levels (low-certainty evidence), while we are uncertain of their effects on such parameters in the NRSIs (very low-certainty evidence). Currently, there is no evidence on the potential effects of statin therapy in people with SLOS regarding survival or QoL, and very limited evidence on the effects on neurobehavioral manifestations. Likewise, current evidence is insufficient and of very low certainty regarding the effects of statins on growth parameters in children with SLOS and plasma or cerebrospinal fluid (CSF) levels of various disease biomarkers. Despite these limitations, current evidence seemingly suggests that statins may increase the risk of adverse reactions in individuals with SLOS receiving statins compared to those who are not. Given the insufficient evidence on potential benefits of statins in individuals with SLOS, and their potential for causing adverse reactions, anyone considering this therapy should take these findings into consideration. Future studies should address the highlighted gaps in evidence on the use of statins in individuals with SLOS by collecting prospective data on survival and performing serial standardized assessments of neurobehavioral features, QoL, anthropometric measures, and plasma and CSF biomarker levels after statin introduction. Future studies should also attempt to use consistent dosages, formulations and durations of cholesterol and statin therapy.

7-Dehydrocholesterol-derived oxysterols cause neurogenic defects in Smith-Lemli-Opitz syndrome.

Defective 3β-hydroxysterol-Δ7 -reductase (DHCR7) in the developmental disorder, Smith-Lemli-Opitz syndrome (SLOS), results in a deficiency in cholesterol and accumulation of its precursor, 7-dehydrocholesterol (7-DHC). Here, we show that loss of DHCR7 causes accumulation of 7-DHC-derived oxysterol metabolites, premature neurogenesis from murine or human cortical neural precursors, and depletion of the cortical precursor pool, both in vitro and in vivo. We found that a major oxysterol, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), mediates these effects by initiating crosstalk between glucocorticoid receptor (GR) and neurotrophin receptor kinase TrkB. Either loss of DHCR7 or direct exposure to DHCEO causes hyperactivation of GR and TrkB and their downstream MEK-ERK-C/EBP signaling pathway in cortical neural precursors. Moreover, direct inhibition of GR activation with an antagonist or inhibition of DHCEO accumulation with antioxidants rescues the premature neurogenesis phenotype caused by the loss of DHCR7. These results suggest that GR could be a new therapeutic target against the neurological defects observed in SLOS.

Evaluation of mutations in DHCR7 gene in high-risk pregnant women for Smith Lemli Opitz Syndrome during second-trimester screening in Nasiriyah

Introduction: Smith Lemli Opitz Syndrome (SLOS) is the second most frequent metabolic disease in various populations. At the end of the cholesterol production pathway, a mutation in the dehydrocholesterol reductase (DHCR7) gene causes SLOS. DHCR7 is a membrane protein that needs the cofactor NADPH to function. In SLOS patients, more than 130 distinct DHCR7 mutations have been discovered. The impact of the DHCR7 gene mutation on the severity and symptoms of SLOS in patients, particularly high-risk pregnant women, has been recommended.&#x0D; Methods: This study was performed on 20 high-risk pregnant women with SLOS at a second-trimester screening in the Nasiriyah. To detect DHCR7 gene mutations in infected individuals, DNA was collected from peripheral blood, and Sanger sequencing was performed.&#x0D; Result: 20 women suspected of having SLOS with 26.7 ±8.01 years old (SD) were included. 70% (14) of families had a history of having a child with SLOS disorder. In contrast, the 30 % (6) remaining families had never had SLOS before and were discovered during pregnancy. Only 4 pregnant women (20%) identified with DHCR7 mutation. The DHCR7 gene was analyzed from exons 1 to 9, and a c.445C&gt; T (CAA-TAA) mutation was detected in exon 6 of this gene.&#x0D; Conclusion: According to the findings of prior studies and the present study, the sequencing of the DHCR7 gene can detect around 96 percent of known variations and pathogens; therefore, the identification and analysis of the DHCR7 gene during pregnancy and screening for SLOS may be claimed to be beneficial.

Measurement of 7-dehydrocholesterol and cholesterol in hair can be used in the diagnosis of Smith-Lemli-Opitz syndrome

7-dehydrocholesterol (7-DHC) and cholesterol (CHOL) are biomarkers of Smith-Lemli-Opitz Syndrome (SLOS), a congenital autosomal recessive disorder characterized by elevated 7-DHC level in patients. Hair samples have been shown to have great diagnostic and research value, which has long been neglected in the SLOS field. In this study, we sought to investigate the feasibility of using hair for SLOS diagnosis. In the presence of antioxidants (2,6-ditert-butyl-4-methylphenol and triphenylphosphine), hair samples were completely pulverized and extracted by micro-pulverized extraction in alkaline solution or in n-hexane. After microwave-assisted derivatization with N,O-Bis(trimethylsilyl)trifluoroacetamide, the analytes were measured by GC-MS. We found that the limits of determination for 7-DHC and CHOL were 10 ng/mg and 8 ng/mg, respectively. In addition, good linearity was obtained in the range of 50–4000 ng/mg and 30–6000 ng/mg for 7-DHC and CHOL, respectively, which fully meets the requirement for SLOS diagnosis and related research. Finally, by applying the proposed method to real hair samples collected from 14 healthy infants and two suspected SLOS patients, we confirmed the feasibility of hair analysis as a diagnostic tool for SLOS. In conclusion, we present an optimized and validated analytical method for the simultaneous determination of two SLOS biomarkers using human hair.

Desmosterol and 7-dehydrocholesterol concentrations in post mortem brains of depressed people: The role of trazodone

Major depressive disorder (MDD) is a common, disabling, and heterogeneous condition that responds unpredictably to current treatments. We previously showed an association between depressive symptoms and plasma concentrations of two cholesterol precursors, desmosterol and 7-dehydrocholesterol (7DHC). Here, we measured total cholesterol and sterol concentrations with mass spectrometry in postmortem brain samples from depressed and control subjects. Mean (±SEM) desmosterol concentration was 8.9 ± 0.97 ng/mg in the depressed versus 10.7 ± 0.72 ng/mg in the control group. The mean of the posterior probability distribution for the difference in desmosterol concentration between the two groups was 2.36 (95% highest density interval [HDI] 0.59–4.17). Mean 7DHC concentrations, 12.5 ± 4.1 ng/mg in the depressed versus 5.4 ± 0.74 ng/mg in the control group, were unlikely to be different (95% HDI, [−1.37–0.34]). We found that presence of trazodone in the peri-mortem toxicology screen accounted for the observed difference in desmosterol concentrations. We also observed extremely high 7DHC levels in all 4 subjects who had taken trazodone. Trazodone has been recently found to inhibit 7-dehydrocholesterol reductase and alter sterol concentrations in rodents, cell culture, human fibroblasts, and blood. In this study, we demonstrate for the first time that trazodone alters human brain sterol composition. Given congenital deficiency of 7-dehydrocholesterol reductase results in Smith-Lemli-Opitz syndrome, our findings support the hypothesis that this commonly used medication may have previously unappreciated risks.

How to Manage Low Estriol Levels in Pregnancies, One Center Experience.

Objective:Low estriol (uE3) levels in the second-trimester screening for Down syndrome may be the result of fetal demise, congenital abnormalities, or some genetic hormonal disorders of the fetus. Although X-linked ichthyosis, a microdeletion syndrome with mild ichthyosis, which causes steroid sulfatase (STS) deficiency, is the most common genetic cause, second-trimester screening tests calculate the risk for a less common and severe disorder known as the Smith Lemli Opitz syndrome (SLOS). We aimed to investigate the outcomes of pregnancies with low uE3 levels in Down syndrome screening and emphasize the high prevalence of STS deficiency instead of SLOS in such cases.Methods:Fifteen pregnancies with very low uE3 levels and high risk for trisomy and/or SLOS in screening tests were evaluated and tested for STS deficiency and SLOS.Results:Seven of the pregnancies had STS microdeletion syndrome, while additional two cases were supposed to have STS gene mutation according to family and/or postnatal history. Although one fetal death was recorded, no chromosomal abnormality, SLOS, or congenital malformation was recorded in our series.Conclusions:SLOS is a very severe and rare syndrome. The risk estimation for SLOS in screening tests causes stress for pregnant women and healthcare givers. We recommend the addition of risk estimation for STS deficiency when a low uE3 level is detected in the screening test.

A reliable tool for detecting 7-dehydrocholesterol and cholesterol in human plasma and its use in diagnosis of Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome is a birth defect caused by the deficiency of 7-dehydrocholesterol reductase in cholesterol biosynthesis pathway, which leads to accumulation of 7-dehydrocholesterol and reduction of cholesterol in body fluids. To effectively diagnose Smith-Lemli-Opitz syndrome and monitor therapy, a reliable method for simultaneous detection of 7-dehydrocholesterol and cholesterol is needed. In the presence of antioxidants (2,6-ditert-butyl-4-methylphenol and triphenylphosphine), 50 μL of human plasma were hydrolyzed at 70℃ for 40min with 1M potassium hydroxide in 90% ethanol, and then 7-dehydrocholesterol and cholesterol were extracted by 600 μL of n-hexane for three times. After microwave-assisted derivatization with 70 μL of N,O-bis(trimethylsilyl)trifluoroacetamide at 460 W for 3min, the analytes were measured by gas chromatography-mass spectrometry. The limits of detection were 100ng/mL for 7-dehydrocholesterol and 300ng/mL for cholesterol. Good linearity was obtained in the range of 1-600μg/mL for 7-dehydrocholesterol and 10-600μg/mL for cholesterol, which completely covered the biochemical levels of Smith-Lemli-Opitz syndrome patients that have been reported. A time-saving and accurate gas chromatography with mass spectrometry based method was developed for the determination of 7-dehydrocholesterol and cholesterol in human plasma, which also serves as a useful tool for Smith-Lemli-Opitz syndrome diagnosis, treatment, and research.

Гипохолестеринемия – важный симптом редких болезней

Hypocholesterolemia is an important symptom that may indicate the presence of severe hereditary metabolic disease or acquired secondary pathology. This lecture discusses the criteria for hypocholesterolemia in children, issues of cholesterol metabolism and its disorders, and the most common causes of hypocholesteremia. Issues of pathogenesis, clinical picture, diagnosis, and treatment of cholesterol synthesis disorders (Smith–Lemli–Opitz syndrome) and abetalipoproteinemia are considered in detail, and clinical cases of patients with these diseases are presented. Key words: hereditary metabolic diseases, hypocholesterolemia, Smith–Lemli–Opitz syndrome, abetalipoproteinemia

Late endosomal/lysosomal accumulation of a neurotransmitter receptor in a cellular model of Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a congenital and developmental malformation syndrome associated with defective cholesterol biosynthesis. It is characterized by accumulation of 7-dehydrocholesterol (the immediate biosynthetic precursor of cholesterol in the Kandutsch-Russell pathway) and an altered cholesterol to total sterol ratio. Because SLOS is associated with neurological malfunction, exploring the function and trafficking of neuronal receptors and their interaction with membrane lipids under these conditions assume significance. In this work, we generated a cellular model of SLOS in HEK-293 cells stably expressing the human serotonin1A receptor (an important neurotransmitter G-protein coupled receptor) using AY 9944, an inhibitor for the enzyme 3β-hydroxy-steroid-∆7 -reductase (7-DHCR). Using a quantitative flow cytometry based assay, we show that the plasma membrane population of serotonin1A receptors was considerably reduced under these conditions without any change in total cellular expression of the receptor. Interestingly, the receptors were trafficked to sterol-enriched LysoTracker positive compartments, which accumulated under these conditions. To the best of our knowledge, our results constitute one of the first reports demonstrating intracellular accumulation and misregulated traffic of a neurotransmitter GPCR in SLOS-like conditions. We believe these results assume relevance in our overall understanding of the molecular basis underlying the functional relevance of neurotransmitter receptors in SLOS.

Biochemical and Clinical Effects of Vitamin E Supplementation in Hungarian Smith-Lemli-Opitz Syndrome Patients.

Smith-Lemli-Opitz syndrome (SLOS) is a severe monogenic disorder resulting in low cholesterol and high 7-dehydrocholesterol (7-DHC) levels. 7-DHC-derived oxysterols likely contribute to disease pathophysiology, and thus antioxidant treatment might be beneficial because of high oxidative stress. In a three-year prospective study, we investigated the effects of vitamin E supplementation in six SLOS patients already receiving dietary cholesterol treatment. Plasma vitamin A and E concentrations were determined by the high-performance liquid chromatography (HPLC) method. At baseline, plasma 7-DHC, 8-dehydrocholesterol (8-DHC) and cholesterol levels were determined by liquid chromatography–tandem mass spectrometry (LC-MS/MS) method. The clinical effect of the supplementation was assessed by performing structured parental interviews. At baseline, patients were characterized by low or low–normal plasma vitamin E concentrations (7.19–15.68 μmol/L), while vitamin A concentrations were found to be normal or high (1.26–2.68 μmol/L). Vitamin E supplementation resulted in correction or significant elevation of plasma vitamin E concentration in all patients. We observed reduced aggression, self-injury, irritability, hyperactivity, attention deficit, repetitive behavior, sleep disturbance, skin photosensitivity and/or eczema in 3/6 patients, with notable individual variability. Clinical response to therapy was associated with a low baseline 7-DHC + 8-DHC/cholesterol ratio (0.2–0.4). We suggest that determination of vitamin E status is important in SLOS patients. Supplementation of vitamin E should be considered and might be beneficial.

Smith-Lemli-Opitz syndrome: Bosnian and Herzegovinian experience

The aim of this paper is to present a patient with the Smith-Lemli-Opitz syndrome (SLOS), with an overview of the modality of diagnosis, and the treatment of the patient. Exome analysis showed two variants in exon 6 of the 7-dehydrocholesterol reductase (DHCR7) gene have been determined: missense variant 1) NM_001360.2: c.470T>C (p.Leu157Pro) and 2) nonsense variant c.452G>A (W151*). Therefore the DHCR7 genotype of the patient is NM_001360.2: c.[470T>C; c.452G>A]. The proband, aged 6 years, has global developmental retardation with missing contact gaze and lacking motor development for her age and with peripheral spastic-enhanced muscle tone, and is under the supervision of children neurologists, gastroenterologists, nephrologists and cardiologists.