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Hayward BE, Kumari D, Usdin K. Recent advances in assays for the fragile X-related disorders. Hum Genet 2017; 136:1313-1327. [PMID: 28866801 DOI: 10.1007/s00439-017-1840-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/24/2017] [Indexed: 12/17/2022]
Abstract
The fragile X-related disorders are a group of three clinical conditions resulting from the instability of a CGG-repeat tract at the 5' end of the FMR1 transcript. Fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI) are disorders seen in carriers of FMR1 alleles with 55-200 repeats. Female carriers of these premutation (PM) alleles are also at risk of having a child who has an FMR1 allele with >200 repeats. Most of these full mutation (FM) alleles are epigenetically silenced resulting in a deficit of the FMR1 gene product, FMRP. This results in fragile X Syndrome (FXS), the most common heritable cause of intellectual disability and autism. The diagnosis and study of these disorders is challenging, in part because the detection of alleles with large repeat numbers has, until recently, been either time-consuming or unreliable. This problem is compounded by the mosaicism for repeat length and/or DNA methylation that is frequently seen in PM and FM carriers. Furthermore, since AGG interruptions in the repeat tract affect the risk that a FM allele will be maternally transmitted, the ability to accurately detect these interruptions in female PM carriers is an additional challenge that must be met. This review will discuss some of the pros and cons of some recently described assays for these disorders, including those that detect FMRP levels directly, as well as emerging technologies that promise to improve the diagnosis of these conditions and to be useful in both basic and translational research settings.
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Affiliation(s)
- Bruce E Hayward
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA
| | - Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA.
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2
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Devillard F, Prieur F, Delhomme-Bachy M, De Freminville B, Lauras B, Brizard CP, Fraisse J, Bertheas MF. Cytogenetic experience in prenatal fra(X) detection on amniotic fluid cultures. Prenat Diagn 1992; 12:613-8. [PMID: 1508852 DOI: 10.1002/pd.1970120708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Since 1987, we have had experience with 13 prenatal diagnoses of 11 women at risk for the fragile X syndrome by cytogenetic studies on amniotic fluid cultures. The induction method included TC 199 medium and methotrexate. Results were obtained in all cases. Ten were males and three were prenatally diagnosed as being affected. Three were females and none of them was fra(X)-positive. Results were confirmed in 10/13 cases. In these cases, we had neither false-positive nor false-negative results.
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Affiliation(s)
- F Devillard
- Department of Haematology, Hôpital Nord, St-Priest-en-Jarez, France
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3
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Kennerknecht I, Baur-Aubele S, Terinde R, Vogel W. Nuclear and chromosomal replication patterns in chorionic villi cells by bromodeoxyuridine labelling and DNA flow cytometry. Cell Prolif 1992; 25:321-36. [PMID: 1643189 DOI: 10.1111/j.1365-2184.1992.tb01443.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Cell kinetics of chorionic villi (CV) were studied by BrdUrd-incorporation detected by fluorescence-plus-Giemsa and BrdUrd-antibody techniques, and by DNA flow cytometry. Growth characteristics of long-term cultures of CV resembled fibroblasts with a total cell cycle time of 26 h, final S phase of 9 h, penultimate S phase of 16 h and G2/M phase of 3-4 h. Especially useful for a quick routine diagnostic approach, Ultroser RG, a commercially available serum supplement, significantly increased cell proliferation and stabilized cell cycle lengths to a total cell cycle time of 14 h, final S phase of 7 h, penultimate S phase of 6 h and G2/M phase of 4 h. Moreover, mitotic activity steadily increased in cultured CV, when studying six successive subculturings. This reflects adaptation to the culture conditions rather than an inherent response of cultured CV cells of increasing passage numbers. Native villi exposed to BrdUrd immediately after biopsy show lower rates of uptake than do aliquots after overnight incubation. As shown by BrdUrd-pulse labelling studies, more than 7 h are required to overcome the proposed 'biopsy stress'. This correlates with routine diagnostic techniques, in which many more metaphase cells are observed in short-term cultures than in direct preparations.
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Howard-Peebles PN, Maddalena A. Recent experience in prenatal diagnosis of fragile X. AMERICAN JOURNAL OF MEDICAL GENETICS 1992; 43:162-6. [PMID: 1605186 DOI: 10.1002/ajmg.1320430126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Our experience with 48 prenatal fragile X cases (35 amniocenteses; 13 chorionic villi samplings) is summarized. Of these 48 cases, 18 consultands were known to be carriers of fragile X. No cytogenetic false negatives or positives were identified but 2 cases were uninterpretable. Cytogenetic recommendations include: 1) Ten or more days recovery time after growth in Chang medium, and 2) use of 3-4 media/inducer systems with duplicate harvests. Direct DNA probe testing will likely be the method of choice for prenatal diagnosis after sufficient data are collected to verify interpretation. Until then, both cytogenetic and direct DNA techniques should be utilized.
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Affiliation(s)
- W T Brown
- Department of Human Genetics, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York
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Pinckert TL. Prenatal diagnosis of genetic disease. Anal Bioanal Chem 1992. [DOI: 10.1007/bf00331931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tommerup N, Søndergaard F, Hanauer A, Oberle I, Bang J, Barbi B, Bech B, Davies K, Froster-Iskenius U, Gustavson KH. Early prenatal diagnosis of the fragile site at Xq27.3 associated with Martin-Bell syndrome. Prenat Diagn 1991; 11:609-19. [PMID: 1685019 DOI: 10.1002/pd.1970110818] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Early prenatal diagnosis of the fragile X was attempted in 44 pregnancies, including one twin pregnancy at risk of Martin-Bell (MB) syndrome. The sex ratio was 24M:21F. The fragile site was reproducibly demonstrated in cultured chorionic villus (CV) cells in eight male and five female fetuses. Six of the male and three of the female fetuses were terminated. Simultaneous RFLP analysis provided confirmative data with flanking DNA markers in 3 of 13 analysed cases. Recombination and/or non-informativeness at available distal and/or proximal loci were found in nine cases. In one male fetus, discordance between the haplotype and cytogenetics (fragile-X-negative) suggested the presence of a normal male transmitter, a double meiotic cross-over within the region, or a false-negative cytogenetic diagnosis. However, discordance between prenatal and post-termination/postnatal cytogenetic findings was not observed in this series. The use of excess thymidine for induction of the fragile X in cultured CV cells provided in the majority of cases a safe and rapid method for cytogenetic diagnosis, with options for early induced termination in fragile-X-positive pregnancies, for simultaneous RFLP analysis, and for subsequent second-trimester analysis of fetal blood in complicated cases.
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Affiliation(s)
- N Tommerup
- John F. Kennedy Institute, Glostrup, Denmark
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Spano LM, Opitz JM. Bibliography on X-linked mental retardation, the fragile X, and related subjects V (1991). AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:173-85. [PMID: 2018055 DOI: 10.1002/ajmg.1320380203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- L M Spano
- Department of Medical Genetics, Shodair Children's Hospital, Helena, Montana 59604
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Cronister A, Hagerman RJ, Wittenberger M, Amiri K. Mental impairment in cytogenetically positive fragile X females. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:503-4. [PMID: 2018094 DOI: 10.1002/ajmg.1320380272] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Prenatal diagnosis is now available to fragile X (fra[X]) syndrome families and has proven reliable when testing male fetuses. It has been reported that approximately one-third of heterozygous fra(X) females demonstrate mental impairment. Based on this, families usually continue pregnancies involving a female fetus. The purpose of this study is to investigate whether a 35% risk for mental impairment is appropriate when counseling heterozygous women carrying fra(X)-positive female fetuses. Forty-three cytogenetically positive (greater than or equal to 2%) daughters of known fra(X) carrier women were ascertained postnatally in an unbiased fashion. Their mother's carrier status was determined on the basis of at least one son with Martin-Bell syndrome. In addition to peripheral blood cytogenetic studies, all daughters had cognitive testing to determine full-scale IQ. In this study, 55.8% (24/43) were mentally impaired (IQ less than 85) compared with the expected 35%. Of these, 42% were mentally retarded (IQ less than 70). Although we do not know the correlation between percent fragility by peripheral blood compared with the percent fragility by amniocentesis or CVS, we assume that they are relatively comparable such that a female who is positive with greater than or equal to 2% fragility would probably be positive by all methods. This report suggests that the penetrance of mental impairment in females with a percent fragility of greater than or equal to 2% may be as high as 55%. Further studies are necessary to clarify this issue so that accurate information can be given in genetic counseling.
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Affiliation(s)
- A Cronister
- Sewall Rehabilitation Center, Denver, CO 80206
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Brown WT, Gross AC, Goonewardena P, Ferrando C, Dobkin C, Jenkins EC. Linkage in fragile X families of three distal flanking markers: ST14, DX13, and F8. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:343-6. [PMID: 1673308 DOI: 10.1002/ajmg.1320380235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The use of linked DNA markers and linkage analysis in the fragile X [fra(X)] syndrome allows for improved genetic counseling and prenatal diagnosis. In order to provide the most accurate information, it is important to determine the order and location and position of flanking markers. Conflicting results have been reported for the order of 3 DNA markers distal to the fra(X) locus. We analyzed the linkage relationships of the distal markers ST14 (DXS52), DX13 (DXS15), and F8 (F8C) in 102 fra(X) families. The results indicated that the 3 DNA markers were closely linked to one another and mapped approximately 11 to 15% recombination units away from the fra(X) locus. The most likely order was fra(X)-DXS52-DXS15-F8. The order fra(X)-DXS52-F8 and 728 times more likely than the order fra(X)-F8-DXS52. One family showed a probable double recombinant: in one individual there was recombination between fra(X)-DXS52 and between DXS52-F8. The low probability of this occurring, 0.3%, raises the possibility of an alternate chromosome arrangement or an unusual recombinant mechanism in some individuals.
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Affiliation(s)
- W T Brown
- Department of Pediatrics, North Shore University Hospital-Cornell University Medical College, Manhasset, N.Y. 11030
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Kennerknecht I, Barbi G, Dahl N, Steinbach P. How can the frequency of false-negative findings in prenatal diagnoses of fra(X) be reduced: experience with first trimester chorionic villi sampling. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:467-75. [PMID: 2018088 DOI: 10.1002/ajmg.1320380266] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report on 12 prenatal diagnoses performed between weeks 10 and 13 on normal women with a well-documented family history of the Martin-Bell syndrome. Seven were obligate and three were potential carriers. One male and 2 female fetuses were found to be fragile X [fra(X)]-positive. The diagnoses were confirmed in fibroblasts or lymphocytes after interruption or postnatally. In one fra(X)-negative female fetus, the analysis of linked DNA markers indicated that most probably she was a heterozygote. Reexamination after birth gave a fra(X)-positive result. Hence this was a case of a false-negative prenatal fra(X) result. The occurrence of false-negative cytogenetic results represents a common problem that limits the sensitivity of prenatal diagnostics in the Martin-Bell syndrome. A study of linked DNA markers can improve the reliability of negative cytogenetic results in first trimester prenatal diagnosis. In case of doubt, the chromosomes could be reexamined after fetal blood sampling.
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Affiliation(s)
- I Kennerknecht
- Abteilung Klinische Genetik, Universität Ulm, Federal Republic of Germany
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Jenkins EC, Krawczun MS, Stark-Houck SL, Duncan CJ, Kunaporn S, Gu H, Schwartz-Richstein C, Howard-Peebles PN, Gross A, Sherman SL. Improved prenatal detection of fra(X)(q27.3): methods for prevention of false negatives in chorionic villus and amniotic fluid cell cultures. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:447-52. [PMID: 1826813 DOI: 10.1002/ajmg.1320380262] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The reliable detection of fra(X)(q27.3) in prenatal samples is important for providing genetic counseling. We have identified 5 new cases of prenatal fragile X [fra(X)] detection in 3 chorionic villus sample (CVS) and 2 amniotic fluid (AF) cell cultures. In 4 of the 5 cases, either excess thymidine (THY) or a combination of THY and 5-fluorodeoxyuridine (FUdR) was clearly superior to FUdR alone as fra(X) inducers. Amniocytes from one case were cultured only in RPMI-1640 and later exposed to FUdR or THY separately. They showed only 2% fra(X) while parallel cultures initiated in Chang medium and incubated in RPMI for at least 7 days (recovery) before fra(X) induction exhibited strikingly increased fra(X) frequencies. Chang medium alone will not allow fra(X) induction in AF (Jenkins EC, Brown WT [1986]: "Genetic Disorders and the Fetus: Diagnosis, Prevention and Treatment." New York: Plenum Press, pp 185-204). Now, using CVS cells, we report that only 1% and 0% fra(X) were detected using FUdR or THY in cells cultured in RPMI for 4 days after removal from Chang medium. Cells with 7 days "recovery" in RPMI exhibited increases from 2 to 6%. Therefore, we have found that Chang medium is very helpful when the appropriate recovery time in another medium is allowed before fra(X) induction. Some false negative reports can be attributed to: induction in Chang medium alone; lack of sufficient recovery time after initiating cells in Chang before induction; and unavailability of the excess THY fra(X) induction system.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- E C Jenkins
- Department of Genetics, New York State Institute for Basic Research in Developmental Disabilities, Staten Island 10314
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Sklower Brooks S, Cohen I, Ferrando C, Jenkins EC, Brown WT, Dobkin C. Cytogenetically negative, linkage positive "fragile X" syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1991; 38:370-3. [PMID: 1673313 DOI: 10.1002/ajmg.1320380242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We investigated the family of a 3-year-old boy with manifestations of the Martin-Bell syndrome (MBS). His 17-year-old cousin had classic manifestations of MBS and was fragile X [fra(X)] positive. The 3-year-old boy was fra(X) negative. Linkage analysis with probes flanking the fra(X) region indicated that these cousins had the same X chromosome inherited from a normal grandfather. The DNA and cytogenetic analyses suggest that limitations in the ability to detect the fra(X) mutation cytogenetically may be responsible for fra(X)-negative MBS; or, alternatively, that a crossover occurred between a locus determining the MBS phenotype and one determining fra(X) expression.
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Affiliation(s)
- S Sklower Brooks
- Department of Human Genetics, New York State Office of Mental Retardation and Developmental Disability, Staten Island 10314
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