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Lalande M, Marchandin H, Enaud L, Carrière C, Rodière M, Astruc J. [Group B streptococcal infection with 2 recurrences in a newborn]. Arch Pediatr 2002; 9:45-8. [PMID: 11865550 DOI: 10.1016/s0929-693x(01)00694-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
UNLABELLED Group B III streptococcus (GBS) is a predominant pathogen in neonates in France. Relapse is rare and two successive relapses are exceptional: only three cases have been yet reported. CASE REPORT A newborn infant of 18 days of age presented a first episode of invasive group B III streptococcal infection with meningitis and ventriculitis. At 53 days of age, a second episode with bacteriemia and parotidis appeared. At 63 days of age, she presented a third episode with meningitis. Genome analysis of the three bacterial strains isolated during the three episodes showed the same clonal origin. COMMENTS We discuss the incidence of the treatment, the eventual presence of a penicillin-tolerant GBS, the possible relapse or recurrence of the pathogen and the role of the relative immunodeficiency in infant.
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Lalande M, Guyon G, Morin C, Reygrobellet C, Rodière M, Astruc J. Formes graves des salmonelloses de l'enfant au chu de Montpellier (1997–2000). Arch Pediatr 2001. [DOI: 10.1016/s0929-693x(01)80199-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lalande M, Rodière M, Astruc J. Céphalhématome infecté et méningite bactérienne néonatale à E. coli. Arch Pediatr 2001. [DOI: 10.1016/s0929-693x(01)80203-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wolverton T, Lalande M. Identification and characterization of three members of a novel subclass of protocadherins. Genomics 2001; 76:66-72. [PMID: 11549318 DOI: 10.1006/geno.2001.6592] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Protocadherins are members of a nonclassic subfamily of calcium-dependent cell-cell adhesion molecules in the cadherin superfamily. Although the extracellular domains have several common structural features, there is no extensive homology between the cytoplasmic domains of protocadherin subfamily members. We have identified a new subclass of protocadherins based on a shared and highly conserved 17-amino-acid cytoplasmic motif. The subclass currently consists of 18 protocadherin members. Two of these, PCDH18 and PCDH19, are novel protocadherins and a third is the human orthologue of mouse Pcdh10. All three genes encode six ectodomain repeats with cadherin-like attributes and, consistent with the structural characteristics of protocadherins, a large first exon encodes the extracellular domain of each gene.
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Cavaillé J, Buiting K, Kiefmann M, Lalande M, Brannan CI, Horsthemke B, Bachellerie JP, Brosius J, Hüttenhofer A. Identification of brain-specific and imprinted small nucleolar RNA genes exhibiting an unusual genomic organization. Proc Natl Acad Sci U S A 2000; 97:14311-6. [PMID: 11106375 PMCID: PMC18915 DOI: 10.1073/pnas.250426397] [Citation(s) in RCA: 471] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have identified three C/D-box small nucleolar RNAs (snoRNAs) and one H/ACA-box snoRNA in mouse and human. In mice, all four snoRNAs (MBII-13, MBII-52, MBII-85, and MBI-36) are exclusively expressed in the brain, unlike all other known snoRNAs. Two of the human RNA orthologues (HBII-52 and HBI-36) share this expression pattern, and the remainder, HBII-13 and HBII-85, are prevalently expressed in that tissue. In mice and humans, the brain-specific H/ACA box snoRNA (MBI-36 and HBI-36, respectively) is intron-encoded in the brain-specific serotonin 2C receptor gene. The three human C/D box snoRNAs map to chromosome 15q11-q13, within a region implicated in the Prader-Willi syndrome (PWS), which is a neurogenetic disease resulting from a deficiency of paternal gene expression. Unlike other C/D box snoRNAs, two snoRNAs, HBII-52 and HBII-85, are encoded in a tandemly repeated array of 47 or 24 units, respectively. In mouse the homologue of HBII-52 is processed from intronic portions of the tandem repeats. Interestingly, these snoRNAs were absent from the cortex of a patient with PWS and from a PWS mouse model, demonstrating their paternal imprinting status and pointing to their potential role in the etiology of PWS. Despite displaying hallmarks of the two families of ubiquitous snoRNAs that guide 2'-O-ribose methylation and pseudouridylation of rRNA, respectively, they lack any telltale rRNA complementarity. Instead, brain-specific C/D box snoRNA HBII-52 has an 18-nt phylogenetically conserved complementarity to a critical segment of serotonin 2C receptor mRNA, pointing to a potential role in the processing of this mRNA.
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Mortier E, Lalande M, Pouchot J, Vinceneux P. Ergotisme après deux comprimés de tartrate d'ergotamine associés à du nelfinavir. Rev Med Interne 2000. [DOI: 10.1016/s0248-8663(00)90232-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Boccaccio I, Glatt-Deeley H, Watrin F, Roëckel N, Lalande M, Muscatelli F. The human MAGEL2 gene and its mouse homologue are paternally expressed and mapped to the Prader-Willi region. Hum Mol Genet 1999; 8:2497-505. [PMID: 10556298 DOI: 10.1093/hmg/8.13.2497] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Prader-Willi syndrome (PWS) is a complex neurogenetic disorder. The phenotype is likely to be a contiguous gene syndrome involving genes which are paternally expressed only, located in the human 15q11-q13 region. Four mouse models of PWS have been reported but these do not definitively allow the delineation of the critical region and the associated genes involved in the aetiology of PWS. Moreover, targeted mutagenesis of mouse homologues of the human candidate PWS genes does not appear to result in any of the features of PWS. Therefore, the isolation of new genes in this region remains crucial for a better understanding of the molecular basis of PWS. In this manuscript, we report the characterization of MAGEL2 and its mouse homologue Magel2. These are located in the human 15q11-q13 and mouse 7C regions, in close proximity to NDN / Ndn. By northern blot analysis we did not detect any expression of MAGEL2 / Magel2 but by RT-PCR analysis, specific expression was detected in fetal and adult brain and in placenta. Both genes are intronless with tandem direct repeat sequences contained within a CpG island in the 5'-untranscribed region. The transcripts encode putative proteins that are homologous to the MAGE proteins and NDN. Moreover, MAGEL2 / Magel2 are expressed only from the paternal allele in brain, suggesting a potential role in the aetiology of PWS and its mouse model, respectively.
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Hibbard MK, Strehl S, Lalande M. Replication timing of CD4 and CD8 in single-positive peripheral blood lymphocytes. Cell Immunol 1999; 198:61-8. [PMID: 10612652 DOI: 10.1006/cimm.1999.1582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The regulatory events leading to the mutually exclusive expression of CD4 and CD8 on peripheral lymphocytes are not fully understood. In particular, the association between DNA replication timing and transcriptional activity of these genes has not been previously investigated. Here, the replication kinetics of the CD4 and CD8 loci in mature single-positive T-cell populations have been examined using a novel approach to the separation of CD4(+) or CD8(+) lymphocytes into discrete cell cycle fractions and a competitive PCR replication timing assay. While the timing of replication of each of these loci is independent of their expression in mature CD4 or CD8 single positive T-cells, the replication of CD8, but not of CD4, shifts to a later time in S phase in transcriptionally silent HS68 fibroblast cells. These findings suggest that changes in DNA replication timing are associated with the developmentally regulated but not with the tissue-specific expression of CD4 and CD8.
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Lalande M, Minassian BA, DeLorey TM, Olsen RW. Parental imprinting and Angelman syndrome. ADVANCES IN NEUROLOGY 1999; 79:421-9. [PMID: 10514831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Angelman syndrome is an inherited disorder that includes severe mental retardation and epilepsy. Patients have no speech, puppet-like gait with jerky movements, hyperactivity, disturbed sleep, bouts of inappropriate laughter, a pronounced jaw, and widely spaced teeth. The syndrome results from deletion or mutation within maternal chromosome 15q11-q13. Considerable evidence suggests that the gene or genes responsible for Angelman syndrome are expressed only from the maternal chromosome 15, a situation known as parental imprinting. This epigenetic marking of certain regions of the parental genomes is characterized by parent-of-origin-specific allelic DNA methylation, allele-specific DNA replication timing, and physical pairing of the two chromosome 15 homologues. Imprinting is important for normal development, and its disregulation causes several human disorders. The epilepsy of Angelman syndrome has been studied and indicates a rather typical electroencephalographic abnormality with slowing and notched wave and spikes. Various types of seizures occur, usually including myoclonus and atypical absence. Variable severity among patients suggests potential molecular diversity in the genetic mechanism, possibly the involvement of more than one gene. Angelman syndrome can arise from the following molecular genetic defects: a deletion in 15q11-q13 that covers the Angelman gene or genes, mutations that alter imprinting, and paternal uni-parental disomy for the region. Another 20% or so of patients with clinical symptoms of Angelman syndrome have none of these three defects but are believed to have mutations in one or more genes in the region, and this may be familial. The UBE3A gene, which codes for the enzyme ubiquitin protein ligase involved in protein degradation and processing, has been found to be mutated in many but not all of patients with Angelman syndrome and can be considered a major Angelman candidate gene. Other potential candidate genes in the region include a cluster of three GABAA receptor subunits, which are involved in inhibitory synaptic transmission in the brain. The GABRB3 gene, which codes for the beta 3 subunit, is deleted in most persons with Angelman syndrome. The absence of this gene in mice causes craniofacial abnormalities and neurologic impairment with seizures. The exact role of UBE3A and GABRB3 in the syndrome and their imprinting status are under investigation.
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Blanpain-Avet P, Fillaudeau L, Lalande M. Investigation of Mechanisms Governing Membrane Fouling and Protein Rejection in the Sterile Microfiltration of Beer with an Organic Membrane. FOOD AND BIOPRODUCTS PROCESSING 1999. [DOI: 10.1205/096030899532367] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Moncla A, Malzac P, Voelckel MA, Auquier P, Girardot L, Mattei MG, Philip N, Mattei JF, Lalande M, Livet MO. Phenotype-genotype correlation in 20 deletion and 20 non-deletion Angelman syndrome patients. Eur J Hum Genet 1999; 7:131-9. [PMID: 10196695 DOI: 10.1038/sj.ejhg.5200258] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Angelman syndrome (AS) is a neurodevelopmental disorder caused by the absence of a maternal contribution to chromosome 15q11-q13. There are four classes of AS according to molecular or cytogenetic status: maternal microdeletion of 15q11-q13 (approximately 70% of AS patients); uniparental disomy (UPD); defects in a putative imprinting centre (IM); the fourth includes 20-30% of AS individuals with biparental inheritance and a normal pattern of allelic methylation in 15q11-q13. Mutations of UBE3A have recently been identified as causing AS in the latter group. Few studies have investigated the phenotypic differences between these classes. We compared 20 non-deletion to 20 age-matched deletion patients and found significant phenotypic differences between the two groups. The more severe phenotype in the deletion group may suggest a contiguous gene syndrome.
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Katz SG, Schneider SS, Bartuski A, Trask BJ, Massa H, Overhauser J, Lalande M, Lansdorp PM, Silverman GA. An 18q- syndrome breakpoint resides between the duplicated serpins SCCA1 and SCCA2 and arises via a cryptic rearrangement with satellite III DNA. Hum Mol Genet 1999; 8:87-92. [PMID: 9887335 DOI: 10.1093/hmg/8.1.87] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 18q-syndrome is representative of a group of terminal deficiency or macrodeletion syndromes characterized by mental retardation and congenital malformations. To gain insight into the mechanism of chromosomal loss and stabilization in these disorders, we cloned a putative terminal deletion breakpoint from an 18q-syndrome patient. The 18q21.3 breakpoint occurred between two nearly identical serine protease inhibitor (serpin) genes, SCCA1 and SCCA2. Although cytogenetic studies suggested that this chromosomal aberration was formed by a simple terminal deletion, DNA sequence analysis, pulsed-field gel electrophoresis and fluorescence in situ hybridization showed that the breakpoint was contiguous with a 35 bp filler sequence followed by a satellite III DNA-containing telomeric fragment of 475-1000 kb. This type of satellite III DNA sequence was not detected on the normal chromosome 18, but was highly homologous with types of satellite III DNA sequences normally located on the short arms (p11) of the acrocentric chromosomes and other heterochromatic regions. This DNA sequence analysis suggested that the terminal deficiency in this 18q-syndrome patient arose via illegitimate (non-homologous) recombination. Moreover, these data raise the possibility that a subset of chromosomal aberrations appearing cytogenetically and molecularly as simple terminal truncations or deletions are caused by small (<1000 kb) cryptic rearrangements.
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Fillaudeau L, Lalande M. A Practical Method to Predict Steady-State Flux and Fouling in the Crossflow Microfiltration of Rough Beer with 1.40 μm Tubular Ceramic Membranes. FOOD AND BIOPRODUCTS PROCESSING 1998. [DOI: 10.1205/096030898532115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Thonneau P, Fougeyrollas B, Ducot B, Boubilley D, Dif J, Lalande M, Soulat C. Complications of abortion performed under local anesthesia. Eur J Obstet Gynecol Reprod Biol 1998; 81:59-63. [PMID: 9846716 DOI: 10.1016/s0301-2115(98)00147-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To assess the incidence of complications of abortion performed under local anesthesia. DESIGN Prospective study. SETTING A family planning center in the Paris area. POPULATION Eight hundred and fifty-eight women admitted for abortion under local anesthesia. MAIN OUTCOME MEASURES Incidence of immediate (the day of vacuum aspiration) and delayed complications (at the follow-up visit 2 weeks after the procedure). RESULTS Among the 858 women who underwent vacuum aspiration, 683 (80%) attended the follow-up visit 2 weeks after the procedure. Fifty-nine percent of the 858 women had not had a previous abortion, 25% had had one, and 16% had had two or more. The average duration of amenorrhea was 8.6 weeks (19% at 6 or 7 weeks, 67% between 8 and 10 weeks, and 14% after 10 weeks). The overall complication rate was 3.4% (23/683) (95% CI=2.0-4.8%). The incidence of immediate complications was 1.7% (15/858) (0.8-2.6%) and that of delayed complications 1.2% (8/683) (0.4-2.0%). CONCLUSION This study confirms the safety and efficacy of abortion by vacuum aspiration under local anesthesia.
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Strehl S, Glatt K, Liu QM, Glatt H, Lalande M. Characterization of two novel protocadherins (PCDH8 and PCDH9) localized on human chromosome 13 and mouse chromosome 14. Genomics 1998; 53:81-9. [PMID: 9787079 DOI: 10.1006/geno.1998.5467] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The protocadherins are a subfamily of the calcium-dependent cell-cell adhesion and recognition proteins of the cadherin superfamily. In this study we describe the isolation and characterization of two novel protocadherins, PCDH8 and PCDH9, that constitute a new linkage group on human chromosome 13 and mouse chromosome 14. Like other protocadherins both genes are predominantly expressed in brain, but PCDH9 is also expressed in a broader variety of tissues, and the expression patterns appear to be developmentally regulated. We have determined the genomic organization of PCDH8, which differs significantly from that of the other cadherin subfamilies. In contrast to the classical and desmosomal cadherins, which in general consist of 15-17 exons and share a remarkable degree of conservation in intron position, PCDH8 consists of only three exons and lacks introns in the extracellular domain. The first exon encodes the extracellular domain, the transmembrane region, and part of the cytoplasmic tail. The second exon encodes the remainder of the cytoplasmic region and is partially untranslated. The differences in the genomic structure of cadherin subfamilies will be discussed in the context of the evolution of the cadherin superfamily.
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Abstract
The clinical features of Angelman syndrome (AS) include microcephaly, severe mental retardation, "puppet-like" ataxic gait with jerky arm movements, hyperactivity, bouts of inappropriate laughter, EEG abnormalities, and seizures. The frequency of occurrence of AS is in the range of 1/10,000 to 1/20,000 births. The AS locus maps to the imprinted chromosome 15q11-q13 region and the disease is caused by the absence of a normal maternal contribution to this region. The genetic complexity of AS is revealed by the existence of at least four molecular classes. A candidate AS gene, ubiquitin protein ligase 3A (UBE3A/E6-AP), has been identified, and mutations of this gene have been detected in several cases of AS. Moreover, UBE3A is expressed predominantly from the maternal allele in brain, strongly supporting its causative role in AS. However, there is evidence to suggest that, in addition to UBE3A, another gene(s) may be involved either directly in AS and/or indirectly by regulating UBE3A expression.
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Ritchie RJ, Mattei MG, Lalande M. A large polymorphic repeat in the pericentromeric region of human chromosome 15q contains three partial gene duplications. Hum Mol Genet 1998; 7:1253-60. [PMID: 9668167 DOI: 10.1093/hmg/7.8.1253] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the identification of a partial duplication of GABRA5 , a gene within the imprinted 15q11-q13 region. The duplicated locus maps to the pericentromeric region of 15q, proximal to the large deletions associated with Angelman and Prader-Willi syndromes. We also observed variation in the number of copies of this locus in different individuals, indicating that the duplication is part of a variable repeat. Investigation of the duplication in individuals with a normal karyotype revealed between one and four copies of the repeat on each chromosome 15, whereas from eight to 20 copies were found in individuals possessing a cytogenetically detectable elongation of the 15q region. The variable region is roughly 1 Mb in size and contains two other non-processed duplications, the immunoglobulin heavy chain (IgH) D segment gene and the neurofibromatosis type 1 (NF1) gene. One unit of the pericentromeric repeat is thus composed of duplications of genes from different chromosomal regions. Moreover, we have found replication asynchrony across the GABRA5 duplication, suggesting for the first time that the imprinted part of chromosome 15q extends proximal of the region commonly deleted in Angelman and Prader-Willi syndromes.
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Buiting K, Dittrich B, Gross S, Lich C, Färber C, Buchholz T, Smith E, Reis A, Bürger J, Nöthen MM, Barth-Witte U, Janssen B, Abeliovich D, Lerer I, van den Ouweland AM, Halley DJ, Schrander-Stumpel C, Smeets H, Meinecke P, Malcolm S, Gardner A, Lalande M, Nicholls RD, Friend K, Schulze A, Matthijs G, Kokkonen H, Hilbert P, Van Maldergem L, Glover G, Carbonell P, Willems P, Gillessen-Kaesbach G, Horsthemke B. Sporadic imprinting defects in Prader-Willi syndrome and Angelman syndrome: implications for imprint-switch models, genetic counseling, and prenatal diagnosis. Am J Hum Genet 1998; 63:170-80. [PMID: 9634532 PMCID: PMC1377255 DOI: 10.1086/301935] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are caused by the loss of function of imprinted genes in proximal 15q. In approximately 2%-4% of patients, this loss of function is due to an imprinting defect. In some cases, the imprinting defect is the result of a parental imprint-switch failure caused by a microdeletion of the imprinting center (IC). Here we describe the molecular analysis of 13 PWS patients and 17 AS patients who have an imprinting defect but no IC deletion. Heteroduplex and partial sequence analysis did not reveal any point mutations of the known IC elements, either. Interestingly, all of these patients represent sporadic cases, and some share the paternal (PWS) or the maternal (AS) 15q11-q13 haplotype with an unaffected sib. In each of five PWS patients informative for the grandparental origin of the incorrectly imprinted chromosome region and four cases described elsewhere, the maternally imprinted paternal chromosome region was inherited from the paternal grandmother. This suggests that the grandmaternal imprint was not erased in the father's germ line. In seven informative AS patients reported here and in three previously reported patients, the paternally imprinted maternal chromosome region was inherited from either the maternal grandfather or the maternal grandmother. The latter finding is not compatible with an imprint-switch failure, but it suggests that a paternal imprint developed either in the maternal germ line or postzygotically. We conclude (1) that the incorrect imprint in non-IC-deletion cases is the result of a spontaneous prezygotic or postzygotic error, (2) that these cases have a low recurrence risk, and (3) that the paternal imprint may be the default imprint.
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Rougeulle C, Cardoso C, Fontés M, Colleaux L, Lalande M. An imprinted antisense RNA overlaps UBE3A and a second maternally expressed transcript. Nat Genet 1998; 19:15-6. [PMID: 9590281 DOI: 10.1038/ng0598-15] [Citation(s) in RCA: 233] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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LaSalle JM, Ritchie RJ, Glatt H, Lalande M. Clonal heterogeneity at allelic methylation sites diagnostic for Prader-Willi and Angelman syndromes. Proc Natl Acad Sci U S A 1998; 95:1675-80. [PMID: 9465075 PMCID: PMC19144 DOI: 10.1073/pnas.95.4.1675] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are developmental disorders resulting from the absence of the paternal or maternal contribution to the 15q11-13 region, respectively. Allele-specific methylation at D15S63 (PW71) has routinely been used as a diagnostic indicator of PWS and AS in DNA samples derived from peripheral blood. Extensive variation in allele-specific methylation patterns, however, has been observed at this site in different tissues, but the frequency or mechanism of this variation has remained uncharacterized. Herein, we have investigated the cellular basis of variation in methylation patterns at four sites of allelic methylation near SNRPN by using DNA samples derived from a panel of primary T lymphocyte clones. Interclonal variability was observed at three of these sites, including the diagnostic PW71 site. Changes in allele-specific methylation patterns occurred at a frequency of about one change in 50% of the cells every 22-25 doublings. In contrast, stable allele-specific methylation was observed in these clonal populations at exon 1 of SNRPN and the androgen receptor locus on the inactive X chromosome, suggesting that methylation at some CpG sites is more faithfully maintained than others. Clonal heterogeneity at PW71 was not an artifact of cell culture because the absence of allelic methylation was also observed in about 20% of the alleles in unstimulated peripheral blood. These results demonstrate that variation in allele-specific methylation at PW71 and other sites in the PWS/AS region appear to depend on the clonal complexity of the particular tissue and on the lack of strict maintenance of methylation within clones.
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Jay P, Rougeulle C, Massacrier A, Moncla A, Mattei MG, Malzac P, Roëckel N, Taviaux S, Lefranc JL, Cau P, Berta P, Lalande M, Muscatelli F. The human necdin gene, NDN, is maternally imprinted and located in the Prader-Willi syndrome chromosomal region. Nat Genet 1997; 17:357-61. [PMID: 9354807 DOI: 10.1038/ng1197-357] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Prader-Willi syndrome (PWS) is a neurogenetic disorder that results from the absence of a normal paternal contribution to the 15q11-13 region. The clinical manifestations of PWS are a transient severe hypotonia in the newborn period, with mental retardation, hypogonadism and obesity observed later in development. Five transcripts with exclusive expression from the paternal allele have been isolated, but none of these has been shown to be involved in PWS. In this study, we report the isolation and characterization of NDN, a new human imprinted gene. NDN is exclusively expressed from the paternal allele in the tissues analysed and is located in the PWS region. It encodes a putative protein homologous to the mouse brain-specific NECDIN protein, NDN; as in mouse, expression in brain is restricted to post-mitotic neurons. NDN displays several characteristics of an imprinted locus, including allelic DNA methylation and asynchronous DNA replication. A complete lack of NDN expression in PWS brain and fibroblasts indicates that the gene is expressed exclusively from the paternal allele in these tissues and suggests a possible role of this new gene in PWS.
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Strehl S, LaSalle JM, Lalande M. High-resolution analysis of DNA replication domain organization across an R/G-band boundary. Mol Cell Biol 1997; 17:6157-66. [PMID: 9315676 PMCID: PMC232466 DOI: 10.1128/mcb.17.10.6157] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Establishing how mammalian chromosome replication is regulated and how groups of replication origins are organized into replication bands will significantly increase our understanding of chromosome organization. Replication time bands in mammalian chromosomes show overall congruency with structural R- and G-banding patterns as revealed by different chromosome banding techniques. Thus, chromosome bands reflect variations in the longitudinal structure and function of the chromosome, but little is known about the structural basis of the metaphase chromosome banding pattern. At the microscopic level, both structural R and G bands and replication bands occupy discrete domains along chromosomes, suggesting separation by distinct boundaries. The purpose of this study was to determine replication timing differences encompassing a boundary between differentially replicating chromosomal bands. Using competitive PCR on replicated DNA from flow-sorted cell cycle fractions, we have analyzed the replication timing of markers spanning roughly 5 Mb of human chromosome 13q14.3/q21.1. This is only the second report of high-resolution analysis of replication timing differences across an R/G-band boundary. In contrast to previous work, however, we find that band boundaries are defined by a gradient in replication timing rather than by a sharp boundary separating R and G bands into functionally distinct chromatin compartments. These findings indicate that topographical band boundaries are not defined by specific sequences or structures.
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Rougeulle C, Glatt H, Lalande M. The Angelman syndrome candidate gene, UBE3A/E6-AP, is imprinted in brain. Nat Genet 1997; 17:14-5. [PMID: 9288088 DOI: 10.1038/ng0997-14] [Citation(s) in RCA: 275] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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