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Jezela-Stanek A, Ciara E, Małunowicz E, Chrzanowska K, Latos-Bieleńska A, Krajewska-Walasek M. Differences between predicted and established diagnoses of Smith-Lemli-Opitz syndrome in the Polish population: underdiagnosis or loss of affected fetuses? J Inherit Metab Dis 2010; 33 Suppl 3:S241-8. [PMID: 20556518 DOI: 10.1007/s10545-010-9132-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 03/26/2010] [Accepted: 05/14/2010] [Indexed: 10/19/2022]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is a metabolic disorder in which an error in cholesterol biosynthesis results in congenital anomalies/mental deficits. The results of our previous newborn screening, based on the carrier frequency of the two most common SLOS-causing mutations in Poland (p.W151X and p.V326L), would make SLOS one of the most frequent recessive disorders in our country (with an incidence of 1:2,300 - 1:3,937). This prompted us to carry out a 3-year (2006-2008) national surveillance program in which about 2,000 physicians were asked to identify potential SLOS patients pre- and postnatally based on clinical identification forms. The incidence of SLOS in Poland was estimated to be from 1:60,941 to 1:105,395 (1: 83,168 ± 22,227) live births, and its 3-year prevalence 1:866,273 ± 16,242. The mean carrier frequency was calculated to be from 1:123 to 1:165. The notable discrepancy between our previous carrier newborn screening and these prospective data may result from reduced fertility in SLOS carriers, intrauterine death of affected fetuses, or underdiagnosis in postnatal life. Since we did not notice significant data supporting the first two aspects, our study may support the suggestion that screening for the most frequent DHCR7 alleles does not reflect the true disease rates in the Polish population. Hence, further studies in which maternal urinary steroids (7-dehydroestriol/estriol and 8-dehydropregnanetriol/pregnanetriol ratios) would serve as screening markers in early pregnancies may be justified.
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Affiliation(s)
- Aleksandra Jezela-Stanek
- Department of Medical Genetics, The Children's Memorial Health Institute, Aleja Dzieci Polskich 20, 04-736 Warsaw, Poland.
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Craig WY, Haddow JE, Palomaki GE, Roberson M. Major fetal abnormalities associated with positive screening tests for Smith-Lemli-Opitz syndrome (SLOS). Prenat Diagn 2007; 27:409-14. [PMID: 17286308 DOI: 10.1002/pd.1699] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Determine the relationship between positive screening interpretations for Smith-Lemli-Opitz syndrome (SLOS) and other fetal abnormalities, to aid counseling and diagnostic activities. METHODS An SLOS screening algorithm was incorporated into California's second-trimester screening program for Down syndrome and open neural tube defects (ONTDs). Between 2002 and 2004, 777 088 pregnant women were given an SLOS risk interpretation, using alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotrophin (hCG) measurements. Outcomes were obtained in 98.8% of screen-positive pregnancies. RESULTS SLOS screen positives, alone or in combination with screen positives for other fetal disorders (Down syndrome, trisomy 18, ONTD), were associated with a high risk for fetal pathology. Type and frequency of chromosomal or anatomic abnormalities (or fetal death) varied according to screen-positive combination. Among 2018 screen-positive pregnancies, 644 fetal deaths were identified. Among the 1374 viable pregnancies, 519 were screen positive for SLOS alone; two SLOS cases and 51 other serious abnormalities were identified (14 aneuploidies; 37 anatomic). The remaining 855 were also screen positive for at least one other disorder; two SLOS cases and 327 other abnormalities were identified (180 aneuploidies; 157 anatomic). CONCLUSION For screening programs implementing the SLOS algorithm, the present data may be useful for counseling and to guide diagnostic studies.
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Ciara E, Popowska E, Piekutowska-Abramczuk D, Jurkiewicz D, Borucka-Mankiewicz M, Kowalski P, Goryluk-Kozakiewicz B, Nowaczyk MJM, Krajewska-Walasek M. SLOS carrier frequency in Poland as determined by screening for Trp151X and Val326Leu DHCR7 mutations. Eur J Med Genet 2006; 49:499-504. [PMID: 16497572 DOI: 10.1016/j.ejmg.2006.01.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 01/17/2006] [Indexed: 11/19/2022]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of cholesterol biosynthesis caused by mutations in the DHCR7 gene. Previous studies estimated the prevalence of SLOS between 1 in 10,000 to 1 in 70,358 based on case frequency surveys. Although panethnic, SLOS appears to be most frequent in Central European populations (Czech Republic 1 in 10,000, Slovakia 1 in 15,000 - 1 in 20,000). In Polish individuals with SLOS two DHCR7 mutations, c.452G>A (p.Trp151X) and c.976G>T (p.Val326Leu), account for 65.2% of all observed DHCR7 mutations. We analyzed 2169 samples for the p.Trp151X mutation and 2087 for the p.Val326Leu mutation. The combined carrier frequency of these two mutations of was 2.40+/-0.32%, yielding a calculated incidence of SLOS in Poland of 2.5 4x10(-4)-4.3 5x10(-4) (1 in 2,300 to 1 in 3,937) placing SLOS among the most common recessive genetic disorders in Poland.
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Affiliation(s)
- E Ciara
- Department of Medical Genetics, Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland.
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Nowaczyk MJM, Waye JS, Douketis JD. DHCR7 mutation carrier rates and prevalence of the RSH/Smith-Lemli-Opitz syndrome: Where are the patients? Am J Med Genet A 2006; 140:2057-62. [PMID: 16906538 DOI: 10.1002/ajmg.a.31413] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
RSH/Smith-Lemli-Opitz (SLOS) is an inborn error of metabolism with protean manifestations. Its exact incidence and prevalence are not known; however, the carrier rate for the most frequently occurring mutation, the null mutation IVS8-1G > C, is approximately 1 in 100 for the Caucasian population in North America (1%) and possibly as high as 1 in 50 to 1 in 30 in Central European populations (2-3.3%). Based on the allele frequencies and the proportion of this mutation observed in various patient populations, the expected incidence of RSH/SLOS in those populations was calculated and reported to be between 1 in 1,590 and 1 in 17,000. However, around the world the observed prevalence and incidence are much lower than those calculated from the individual mutation carrier rates observed in any given population. The discrepancy between the expected incidence and prevalence can be explained only in part by the neonatal and infancy deaths of the most severely affected children with RSH/SLOS and the under ascertainment of mild and atypical cases at the mild end of the spectrum. RSH/SLOS may be responsible for a high number of miscarriages. Recent observations estimate the prevalence of SLOS at 16 weeks of gestation as similar to that observed at birth (approximately 1 in 60,000) suggesting that either reduced fertility of carrier couples or losses of affected embryos or fetuses in the first trimester play a significant role in reducing the second trimester prevalence of RSH/SLOS. It is possible that the estimates of carrier rates based on population screening for the most commonly occurring mutations may not reflect the true carrier rates in the population. In order to reconcile the above-mentioned paradoxes, we propose a model based on a higher than observed carrier frequency of the most common mutation and on very high fetal loss of homozygotes for that mutation.
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Craig WY, Haddow JE, Palomaki GE, Kelley RI, Kratz LE, Shackleton CHL, Marcos J, Stephen Tint G, MacRae AR, Nowaczyk MJ, Kloza EM, Irons MB, Roberson M. Identifying Smith–Lemli–Opitz syndrome in conjunction with prenatal screening for Down syndrome. Prenat Diagn 2006; 26:842-9. [PMID: 16832833 DOI: 10.1002/pd.1518] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Smith-Lemli-Opitz syndrome (SLOS) is a rare hereditary disorder of cholesterol metabolism. We examine the feasibility of identifying SLOS as a part of a routine prenatal screening and evaluate diagnostic testing in maternal urine (or serum), in addition to amniotic fluid. METHODS Our SLOS risk algorithm utilized three Down syndrome screening markers (estimated 62% detection rate; 0.3% screen-positive rate). Fifteen North American prenatal screening programs implemented this algorithm. RESULTS SLOS risk was assigned to 1 079 301 pregnancies; 3083 were screen-positive (0.29%). Explanations were found for 1174, including 914 existing fetal deaths. Among the remaining pregnancies, 739 were screen-positive only for SLOS; 1170 were also screen-positive for other fetal disorders. Five of six SLOS pregnancies (83%) were screen-positive. All six had sonographic findings, were biochemically confirmed, and were terminated. Maternal urine steroid measurements were confirmatory in four cases tested. Second-trimester prevalence among Caucasians was 1 in 101 000 (1 in 130 000 overall; no cases in other racial groups). Among 739 pregnancies screen-positive only for SLOS, two cases were identified; another 69 had major fetal abnormalities. CONCLUSIONS Although SLOS occurred less often than previously reported, many other major abnormalities were detected. Implementing the algorithm as an adjunct to Down syndrome screening may be feasible.
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Abstract
Zusammenfassung: Die Ursachen für Autismus sind heterogen und ganz überwiegend genetischer Natur. Eine exakte benennbare Ätiologie wird in weniger als 10% der Fälle gefunden. Die Enttäuschung über den geringen Erfolg bei der Ursachenfindung und zahlreiche Berichte über die Assoziation von Autismus mit Stoffwechselerkrankungen sowie über «Wunderheilungen» bei unterschiedlichsten medikamentösen oder diätetischen Therapien haben bei vielen Ärzten und Eltern zu einer zunehmenden Unsicherheit über die sinnvolle Diagnostik und Behandlung geführt. Diese Arbeit gibt einen Überblick über seltene angeborene Stoffwechselerkrankungen («inborn errors of metabolism»), die nachweislich (z.B. Phenylketonurie, Smith-Lemli-Opitz Syndrom) oder wahrscheinlich (z.B. Succinat-Semialdehyd-Dehydrogenase-Mangel) mit Autismus-spezifischen Symptomen vergesellschaftet sind. In aller Regel weisen betroffene Patienten zusätzliche neurologische Symptome auf. Es werden die zur Diagnostik dieser angeborenen Stoffwechselerkrankungen notwendigen Untersuchungen und mögliche therapeutische Maßnahmen dargestellt. Neben diesen gut definierten Stoffwechselerkrankungen mit der Möglichkeit einer rationalen Therapie wird auch auf Hypothesen über die Entstehung von Autismus durch «Stoffwechselveränderungen» eingegangen, die entweder nicht bewiesen oder nachweislich falsch sind.
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Affiliation(s)
- Andreas Hahn
- Abteilung Neuropädiatrie und Sozialpädiatrie, Zentrum Kinderheilkunde, Justus-Liebig-Universität, Giessen.
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Matsumoto Y, Morishima KI, Honda A, Watabe S, Yamamoto M, Hara M, Hasui M, Saito C, Takayanagi T, Yamanaka T, Saito N, Kudo H, Okamoto N, Tsukahara M, Matsuura S. R352Q mutation of the DHCR7 gene is common among Japanese Smith-Lemli-Opitz syndrome patients. J Hum Genet 2005; 50:353-356. [PMID: 16044199 DOI: 10.1007/s10038-005-0267-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 06/06/2005] [Indexed: 10/25/2022]
Abstract
Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive malformation syndrome characterized by microcephaly, syndactyly of toes, ambiguous genitalia, and mental retardation. The underlying DHCR7 gene has been identified and a wide variety of distinct mutations were reported in USA and European SLOS patients. A significant difference has been suggested in the frequency of SLOS among different ethnic populations. Here, we report mutational analysis of seven Japanese SLOS patients. Five mutations, R352Q, R242H, G303R, X476Q, and S192F, were identified, and R352Q appeared most frequent, since nine out of the 13 mutations of Japanese origin were the same R352Q. These results suggest that R352Q is a predominant founder mutation in Japanese SLOS patients.
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Affiliation(s)
- Yoshiyuki Matsumoto
- Department of Radiation Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Ken-Ichi Morishima
- Department of Radiation Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Akira Honda
- Department of Gastroenterology, University of Tsukuba, Tsukuba, Japan
| | - Shoji Watabe
- Faculty of Health Sciences, Yamaguchi University School of Medicine, Ube, Japan
| | - Misa Yamamoto
- Faculty of Health Sciences, Yamaguchi University School of Medicine, Ube, Japan
| | - Masayuki Hara
- General Isotope Center, Tokyo Medical and Dental University, Tokyo, Japan
| | | | - Chikako Saito
- Department of Psychiatrics, National Sanatorium Hokuriku Hospital, Joe-hana, Japan
| | | | - Tsutomu Yamanaka
- Department of Human Welfare, Okazaki Women's Junior College, Okazaki, Japan
| | | | - Hideaki Kudo
- Asahigawasou Ryoiku Center Ryoikuen, Okayama, Japan
| | - Nobuhiko Okamoto
- Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka, Japan
| | - Masato Tsukahara
- Faculty of Health Sciences, Yamaguchi University School of Medicine, Ube, Japan
| | - Shinya Matsuura
- Department of Radiation Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
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Yu H, Wessels A, Chen J, Phelps AL, Oatis J, Tint GS, Patel SB. Late gestational lung hypoplasia in a mouse model of the Smith-Lemli-Opitz syndrome. BMC Dev Biol 2004; 4:1. [PMID: 15005800 PMCID: PMC341451 DOI: 10.1186/1471-213x-4-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2003] [Accepted: 02/02/2004] [Indexed: 11/24/2022]
Abstract
Background Normal post-squalene cholesterol biosynthesis is important for mammalian embryonic development. Neonatal mice lacking functional dehydrocholesterol Δ7-reductase (Dhcr7), a model for the human disease of Smith-Lemli-Opitz syndrome, die within 24 hours of birth. Although they have a number of biochemical and structural abnormalities, one cause of death is from apparent respiratory failure due to developmental pulmonary abnormalities. Results In this study, we characterized further the role of cholesterol deficiency in lung development of these mice. Significant growth retardation, beginning at E14.5~E16.5, was observed in Dhcr7-/- embryos. Normal lobation but smaller lungs with a significant decrease in lung-to-body weight ratio was noted in Dhcr7-/- embryos, compared to controls. Lung branching morphogenesis was comparable between Dhcr7-/- and controls at early stages, but delayed saccular development was visible in all Dhcr7-/- embryos from E17.5 onwards. Impaired pre-alveolar development of varying severity, inhibited cell proliferation, delayed differentiation of type I alveolar epithelial cells (AECs) and delayed vascular development were all evident in knockout lungs. Differentiation of type II AECs was apparently normal as judged by surfactant protein (SP) mRNAs and SP-C immunostaining. A significant amount of cholesterol was detectable in knockout lungs, implicating some maternal transfer of cholesterol. No significant differences of the spatial-temporal localization of sonic hedgehog (Shh) or its downstream targets by immunohistochemistry were detected between knockout and wild-type lungs and Shh autoprocessing occurred normally in tissues from Dhcr7-/- embryos. Conclusion Our data indicated that cholesterol deficiency caused by Dhcr7 null was associated with a distinct lung saccular hypoplasia, characterized by failure to terminally differentiate alveolar sacs, a delayed differentiation of type I AECs and an immature vascular network at late gestational stages. The molecular mechanism of impaired lung development associated with sterol deficiency by Dhcr7 loss is still unknown, but these results do not support the involvement of dysregulated Shh-Patched-Gli pathway in causing this defect.
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Affiliation(s)
- Hongwei Yu
- Division of Endocrinology, Diabetes and Medical Genetics, Medical University of South Carolina, STR 541, 114 Doughty Street, Charleston, SC 29403, USA
| | - Andy Wessels
- Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, SC 29403, USA
| | - Jianliang Chen
- Division of Endocrinology, Diabetes and Medical Genetics, Medical University of South Carolina, STR 541, 114 Doughty Street, Charleston, SC 29403, USA
| | - Aimee L Phelps
- Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, SC 29403, USA
| | - John Oatis
- Division of Endocrinology, Diabetes and Medical Genetics, Medical University of South Carolina, STR 541, 114 Doughty Street, Charleston, SC 29403, USA
| | - G Stephen Tint
- Research Service, Department of Veterans Affairs New Jersey Health Care System, East Orange, NJ, USA and Medical Service, UMDNJ-New Jersey Medical School, Newark, NJ, USA
| | - Shailendra B Patel
- Division of Endocrinology, Diabetes and Medical Genetics, Medical University of South Carolina, STR 541, 114 Doughty Street, Charleston, SC 29403, USA
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Schoen E, Norem C, O'Keefe J, Krieger R, Walton D, To TT. Maternal serum unconjugated estriol as a predictor for Smith-Lemli-Opitz syndrome and other fetal conditions. Obstet Gynecol 2003; 102:167-72. [PMID: 12850625 DOI: 10.1016/s0029-7844(03)00370-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To assess the clinical value of low maternal serum unconjugated estriol (E3) level for diagnosing Smith-Lemli-Opitz syndrome and other fetal clinical conditions in pregnant members of a large health maintenance organization. METHODS We studied serum unconjugated E3 levels in 120,071 gravidas having California Expanded Alpha-Fetoprotein prenatal screening at 15-20 weeks' gestation during a 5-year period. RESULTS Of the 120,071 women, 323 (0.27%) had low unconjugated E3 levels (less than or equal to 0.2 ng/mL, or 0.15 multiples of the median). Excluding women who were screened too early or who had indeterminate screening results, 103 (0.08%) women with unexplained low unconjugated E3 level remained; of these 103 women, 33 had negative screening results and 68 had positive screening results, and two were tested too late for interpretation. Intrauterine fetal death occurred in 39 (57%) of the 68 women with low unconjugated E3 and positive screening results and occurred in two (6%) of the 33 women with low unconjugated E3 levels and negative screening results, a significant difference (P <.001). Two cases of Smith-Lemli-Opitz syndrome were identified and the patients did not survive the neonatal period; one was a therapeutic abortion for severe oligohydramnios, and the other died at age 48 hours. Low unconjugated E3 level also predicted presence of steroid sulfatase deficiency, a much more common X-linked skin disorder characterized by ichthyosis. CONCLUSION Low maternal serum unconjugated E3 diagnosed more cases of steroid sulfatase deficiency and undetected intrauterine fetal death than Smith-Lemli-Opitz syndrome (1:60,000 prevalence), although the clinical importance of having this information prenatally is uncertain.
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Affiliation(s)
- Edgar Schoen
- Regional Perinatal Screening Program, Department of Genetics and Perinatology, Kaiser Permanente Medical Center, Oakland, California 94611-5693, USA.
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Abstract
Smith-Lemli-Opitz syndrome, a severe developmental disorder associated with multiple congenital anomalies, is caused by a defect of cholesterol biosynthesis. Low cholesterol and high concentrations of its direct precursor, 7-dehydrocholesterol, in plasma and tissues are the diagnostic biochemical hallmarks of the syndrome. The plasma sterol concentrations correlate with severity and disease outcome. Mutations in the DHCR7 gene lead to deficient activity of 7-dehydrocholesterol reductase (DHCR7), the final enzyme of the cholesterol biosynthetic pathway. The human DHCR7 gene is localised on chromosome 11q13 and its structure has been characterized. Ninety-one different mutations in the DHCR7 gene have been published to date. This paper is a review of the clinical, biochemical and molecular genetic aspects.
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Affiliation(s)
- P E Jira
- Department of Pediatrics, University Medical Centre Nijmegen, 6500 HB Nijmegen, the Netherlands
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Martínez-Frías ML, Bermejo E, Rodríguez-Pinilla E. Incidence of Smith-Lemli-Opitz syndrome in Ontario, Canada. Am J Med Genet A 2003; 116A:101; author reply 102. [PMID: 12476463 DOI: 10.1002/ajmg.a.10838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Nowaczyk MJ, Nakamura LM, Waye JS. DHCR7 and Smith-Lemli-Opitz syndrome. CLIN INVEST MED 2001; 24:311-7. [PMID: 11767235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- M J Nowaczyk
- Department of Pathology and Molecular Medicine, McMaster University and Hamilton Regional Laboratory Medicine Program, Ont.
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Abstract
Smith-Lemli-Opitz syndrome (OMIM 270400) (SLOS) is caused by inherited enzymatic deficiency of 3beta-hydroxysterol-Delta7-reductase (7-dehydrocholesterol-Delta7-reductase, DHCR7). SLOS is diagnosed clinically by the demonstration of elevated levels of 7-dehydrocholesterol (7DHC) in body fluids or tissues. SLOS is associated with mental retardation of variable degree and severe behavior abnormalities. The physical abnormalities range from minor facial anomalies to lethal malformations of the central nervous system, heart, kidneys, and other organs. The exact incidence of SLOS is not known. Although there exist estimates of the incidence of SLOS ranging from 1 in 20,000 to 1 in 60,000, no prospective studies of the incidence of SLOS, based on the clinical data and biochemical diagnosis of SLOS, have been performed. Five unrelated cases of SLOS were diagnosed in Ontario during a 12-month period. The diagnoses were made based on the demonstration of elevated 7DHC in plasma or amniotic fluid. The birth rate for Ontario for that period was 132,000 births. The incidence of SLOS in Ontario was at least 1 in 26,500 pregnancies in 1999-2000. Given that 86% of the population of Ontario is of European origin, the incidence of SLOS in the Ontario population of European origin was at least 1 in 22,700. As infants with mild forms of SLOS born during this period may remain undiagnosed, these numbers likely are underestimates. This observation has implications for prenatal and newborn screening for this potentially treatable inherited disorder.
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Affiliation(s)
- M J Nowaczyk
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.
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Abstract
The brief history of the Smith-Lemli-Opitz syndrome (SLOS) (MIM 270400) reflects that of latter 20th century dysmorphology and biochemical and molecular genetics: from its first description as a rare but characteristic multiple malformation syndrome known only to a handful of dysmorphologists, to a relatively common Garrodian defect with a complex molecular basis that has captured the attention of researchers and basic scientists from the fields as diverse as embryology, developmental biology, sterol biochemistry, epidemiology, and teratology. The discovery of the underlying biochemical defect - deficiency of 3beta-hydroxysteroid-Delta7-reductase (DHCR7), an enzyme catalyzing the last step of cholesterol biosynthesis, and the resultant generalized cholesterol deficiency - has led to an explosion of knowledge of this biochemical pathway and to a paradigm shift in the recognition of metabolic deficiencies as causes of dysmorphic syndromes. Characterization of the human DHCR7 gene and the identification of mutations in patients with SLOS have revealed a complex picture of molecular heterogeneity and provided insights into the structure and function of DHCR7. SLOS is the first metabolic malformation syndrome with profound effects on the body plan, and its discovery has paved the way to the discovery of a number of other defects of the cholesterol synthetic pathway.
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Affiliation(s)
- M J Nowaczyk
- Department of Pathology and Molecular Medicine, McMaster University Medical Centre, 1200 Main Street West, Hamilton, Ontario, Canada L8S 4J9.
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Witsch-Baumgartner M, Fitzky BU, Ogorelkova M, Kraft HG, Moebius FF, Glossmann H, Seedorf U, Gillessen-Kaesbach G, Hoffmann GF, Clayton P, Kelley RI, Utermann G. Mutational spectrum in the Delta7-sterol reductase gene and genotype-phenotype correlation in 84 patients with Smith-Lemli-Opitz syndrome. Am J Hum Genet 2000; 66:402-12. [PMID: 10677299 PMCID: PMC1288092 DOI: 10.1086/302760] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Smith-Lemli-Opitz syndrome (SLOS), an autosomal recessive malformation syndrome, ranges in clinical severity from mild dysmorphism and moderate mental retardation to severe congenital malformation and intrauterine lethality. Mutations in the gene for Delta7-sterol reductase (DHCR7), which catalyzes the final step in cholesterol biosynthesis in the endoplasmic reticulum (ER), cause SLOS. We have determined, in 84 patients with clinically and biochemically characterized SLOS (detection rate 96%), the mutational spectrum in the DHCR7 gene. Forty different SLOS mutations, some frequent, were identified. On the basis of mutation type and expression studies in the HEK293-derived cell line tsA-201, we grouped mutations into four classes: nonsense and splice-site mutations resulting in putative null alleles, missense mutations in the transmembrane domains (TM), mutations in the 4th cytoplasmic loop (4L), and mutations in the C-terminal ER domain (CT). All but one of the tested missense mutations reduced protein stability. Concentrations of the cholesterol precursor 7-dehydrocholesterol and clinical severity scores correlated with mutation classes. The mildest clinical phenotypes were associated with TM and CT mutations, and the most severe types were associated with 0 and 4L mutations. Most homozygotes for null alleles had severe SLOS; one patient had a moderate phenotype. Homozygosity for 0 mutations in DHCR7 appears compatible with life, suggesting that cholesterol may be synthesized in the absence of this enzyme or that exogenous sources of cholesterol can be used.
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Affiliation(s)
- M Witsch-Baumgartner
- Institute of Medical Biology and Human Genetics, Schoepfstrasse 41, 6020 Innsbruck, Austria
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Nowaczyk MJ, Whelan DT, Heshka TW, Hill RE. Smith-Lemli-Opitz syndrome: a treatable inherited error of metabolism causing mental retardation. CMAJ 1999; 161:165-70. [PMID: 10439827 PMCID: PMC1230468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
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.
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Affiliation(s)
- M J Nowaczyk
- Department of Pathology and Molecular Medicine, Hamilton Health Sciences Corporation, Ont.
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Tsukahara M, Fujisawa K, Yamamoto K, Hasui M, Saito C, Yamamaka T, Honda A, Honda M, Tint GS, Salen G, Opitz JM. Smith-Lemli-Opitz syndrome in Japan. Am J Med Genet 1998; 75:118-9. [PMID: 9450870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Abstract
Infants with infantile hypertrophic pyloric stenosis (IHPS) born from 1983 to 1988 and recorded in the California Birth Defects Monitoring Program (CBDMP) database were compared with their birth cohort by demographic characteristics and selected associated birth defects. We identified 1963 cases of IHPS for a cumulative incidence of 1.9 per 1000 livebirths. The cumulative incidence per 1000 livebirths was 2.4 in White, 1.8 in Hispanic, 0.7 in Black, and 0.6 in Asian infants. Between weeks 3-12 after birth, 1871 (95%) IHPS cases were diagnosed. Premature infants were diagnosed with IHPS later than term or post-term infants. The incidence of IHPS declined for those born to maternal age groups of > or = 25 years and, independently, for successive birth ranks. The probandwise concordance rate for IHPS in monozygous twins was less than unity (0.25-0.44), although higher than the concordance for dizygous twins (0.05-0.10). The incidence of Smith-Lemli-Opitz syndrome (SLO) diagnosed in infants with IHPS (3 of 1963) was 157-fold higher than the incidence of SLO diagnosed in the CBDMP population. IHPS occurs in all of the largest racial and ethnic groups in California, most frequently in White and Hispanic infants. Pyloric stenosis presents only within a brief phase of development, which may be delayed in premature infants. A predominant discordance of disease state in monozygous twins implies an aetiological role for undetermined environmental factors. The association between SLO, caused by deficient cholesterol synthesis, and IHPS deserves additional study. Infants with suspected SLO require close observation for the onset of IHPS.
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Affiliation(s)
- R Schechter
- California Department of Health Services, Berkeley 94704, USA
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Salen G, Shefer S, Batta AK, Tint GS, Xu G, Honda A, Irons M, Elias ER. Abnormal cholesterol biosynthesis in the Smith-Lemli-Opitz syndrome. J Lipid Res 1996; 37:1169-80. [PMID: 8808751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The Smith-Lemli-Opitz syndrome is caused by an inherited defect in 7-dehydrocholesterol-delta7-reductase, the enzyme that catalyzes the last reaction in cholesterol biosynthesis, the conversion of 7-dehydrocholesterol to cholesterol. As a result, deficient cholesterol is produced and the precursor 7-dehydrocholesterol and derivatives (8-dehydrocholesterol and 19-nor-5,7,9(10)-cholestatrien-3 beta-ol) accumulate. Tissues (especially brain) deprived of cholesterol, or because of the deposited sterol precursors and derivatives, develop abnormally and function poorly. Replacement with dietary cholesterol may help correct the biochemical defects and improve symptoms.
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Affiliation(s)
- G Salen
- VA Medical Center, East Orange, NJ 07019, USA
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