Publications by authors named "Francesca Cogliati"

14 Publications

  • Page 1 of 1

Pathogenic Variants in and in Genes for GABAa Receptor Subunities Cause Atypical Rett/Rett-like Phenotypes.

Int J Mol Sci 2019 Jul 24;20(15). Epub 2019 Jul 24.

Istituto Auxologico Italiano, IRCCS, Cytogenetics and Molecular Genetics Laboratory, 20145 Milan, Italy.

Rett syndrome (RTT) is a neurodevelopmental disorder, affecting 1 in 10,000 girls. Intellectual disability, loss of speech and hand skills with stereotypies, seizures and ataxia are recurrent features. Stringent diagnostic criteria distinguish classical Rett, caused by a pathogenic variant in 95% of cases, from atypical girls, 40-73% carrying variants, and rarely and alterations. A large fraction of atypical and RTT-like patients remain without genetic cause. Next Generation Sequencing (NGS) targeted to multigene panels/Whole Exome Sequencing (WES) in 137 girls suspected for RTT led to the identification of a de novo variant in gene in four atypical RTT and two RTT-like girls. De novo pathogenic variants-one in and, for first time, one in -were disclosed in classic and atypical RTT patients. Interestingly, the variant occurred at low rate percentage in blood and buccal swabs, reinforcing the relevance of mosaicism in neurological disorders. We confirm the role of in atypical RTT/RTT-like patients if early psychomotor delay and epilepsy before 2 years of age are observed, indicating its inclusion in the RTT diagnostic panel. Lastly, we report pathogenic variants in Gamma-aminobutyric acid-A (GABAa) receptors as a cause of atypical/classic RTT phenotype, in accordance with the deregulation of GABAergic pathway observed in defective and models.
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http://dx.doi.org/10.3390/ijms20153621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6696386PMC
July 2019

Analysis of the Phenotypes in the Rett Networked Database.

Int J Genomics 2019 27;2019:6956934. Epub 2019 Mar 27.

Medical Genetics, University of Siena, Italy.

Rett spectrum disorder is a progressive neurological disease and the most common genetic cause of intellectual disability in females. is the major causative gene. In addition, and mutations have been reported in Rett patients, especially with the atypical presentation. Each gene and different mutations within each gene contribute to variability in clinical presentation, and several groups worldwide performed genotype-phenotype correlation studies using cohorts of patients with classic and atypical forms of Rett spectrum disorder. The Rett Networked Database is a unified registry of clinical and molecular data of Rett patients, and it is currently one of the largest Rett registries worldwide with several hundred records provided by Rett expert clinicians from 13 countries. Collected data revealed that the majority of -mutated patients present with the classic form, the majority of -mutated patients with the early-onset seizure variant, and the majority of -mutated patients with the congenital form. A computation of severity scores further revealed significant differences between groups of patients and correlation with mutation types. The highly detailed phenotypic information contained in the Rett Networked Database allows the grouping of patients presenting specific clinical and genetic characteristics for studies by the Rett community and beyond. These data will also serve for the development of clinical trials involving homogeneous groups of patients.
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http://dx.doi.org/10.1155/2019/6956934DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6458890PMC
March 2019

Recurrence and Familial Inheritance of Intronic Pathogenic Variant Associated With Mild CdLS.

Front Neurol 2018 27;9:967. Epub 2018 Nov 27.

Laboratorio di Ricerche di Citogenetica Medica e Genetica Molecolare, Istituto Auxologico Italiano (IRCCS) Milan, Italy.

Splicing pathogenic variants account for a notable fraction of alterations underlying Cornelia de Lange syndrome but are likely underrepresented, due to overlooking of non-canonical intronic variants by traditional and contemporary sequencing methods. We describe five subjects, belonging to three families, displaying a mild Cornelia de Lange syndrome phenotype who carry the pathogenic variant c.5329-15A>G, affecting the IVS27 branch site, yet reported in a single case. By RNA analysis we evidenced two alternative transcripts: the exon 28 in frame skipped transcript, described in the published case and an out-of-frame transcript retaining 14 nucleotides of IVS27 3'end. Even if both aberrant transcripts are at negligible levels, their presence justifies the CdLS phenotype shared by our patients consisting of borderline-mild cognitive impairment and slight but typical facial dysmorphisms. Transmission of the pathogenic variant from pauci-symptomatic mother to her siblings emphasizes the need of molecular diagnosis extended to deep intronic regions in patients with subtle but recognizable CdLS phenotype.
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http://dx.doi.org/10.3389/fneur.2018.00967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6277459PMC
November 2018

The phenotype of developmental and epileptic encephalopathy.

Neurology 2018 09 31;91(12):e1112-e1124. Epub 2018 Aug 31.

From the Department of Clinical Neurophysiology (E.G., S.B.), Danish Epilepsy Centre, Dianalund; Institute for Regional Health Services (E.G., K.M.J., R.S.M.), University of Southern Denmark, Odense, Denmark; Neuroscience Department (C.M., R.G., M.M.), Children's Hospital A. Meyer, University of Florence; Department of Neuroscience (M.T., N.S., F.V.), Bambino Gesù Children's Hospital, IRCCS, Rome, Italy; Division of Neurology (M.P.F., I.H.), The Children's Hospital of Philadelphia; Departments of Pediatrics and Neurology (M.P.F., I.H.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia; Universitätskinderklinik Tübingen (M.A., M.W.), Germany; Department of Neurology (K.H.), Royal Children's Hospital Melbourne; Department of Paediatrics (K.H.), University of Melbourne; Australia Neurosciences Group (K.H.), Murdoch Children's Research Institute, Melbourne, Australia; Servizio di Neuropsichiatria Infantile (F.D., E.F.), Policlinico G.B. Rossi, Universita Degli Studi di Verona; Department of Child Neurology (S.S., G.A.), Ospedale Pediatrico G. Salesi-Ospedali Riuniti, Ancona, Italy; Division of Clinical Neurophysiology (B.B.), Children's Research Center, University Children's Hospital Zurich, Switzerland; Brain and Behaviour Department (S.M.), University of Pavia; Department of Pediatric Neuroradiology (A.P.), IRCCS "C. Mondino" National Neurological Institute, Pavia, Italy; Department of Epilepsy Genetics (K.J., R.S.M.), Danish Epilepsy Centre Dianalund; Department of Child Neurology (B.J.), Danish Epilepsy Centre, Dianalund, Denmark; Cytogenetic and Molecular Genetic Laboratory (S.R., F.C.), Istituto Auxologico Italiano, IRCCS, Milano, Italy; Department of Adult Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Struttura Complessa di Neurologia Pediatrica Ospedale Vittore Buzzi (P.V.), Milano; Dipartimento di Scienze Biomediche e Cliniche L. Sacco (P.V.), Università di Milano, Italy; Århus University (S.B.), Denmark; Department of Child Neurology (I.E.S.), University of Melbourne, Austin Health, Florey Institute; and Department of Child Neurology (I.E.S.), The Royal Children's Hospital, Melbourne, Australia.

Objective: To delineate the electroclinical features of infantile developmental and epileptic encephalopathy (EIEE13, OMIM #614558).

Methods: Twenty-two patients, aged 19 months to 22 years, underwent electroclinical assessment.

Results: Sixteen of 22 patients had mildly delayed development since birth. Drug-resistant epilepsy started at a median age of 4 months, followed by developmental slowing, pyramidal/extrapyramidal signs (22/22), movement disorders (12/22), cortical blindness (17/22), sialorrhea, and severe gastrointestinal symptoms (15/22), worsening during early childhood and plateauing at age 5 to 9 years. Death occurred in 4 children, following extreme neurologic deterioration, at 22 months to 5.5 years. Nonconvulsive status epilepticus recurred in 14 of 22 patients. The most effective antiepileptic drugs were oxcarbazepine, carbamazepine, phenytoin, and benzodiazepines. EEG showed background deterioration, epileptiform abnormalities with a temporo-occipital predominance, and posterior delta/beta activity correlating with visual impairment. Video-EEG documented focal seizures (FS) (22/22), spasm-like episodes (8/22), cortical myoclonus (8/22), and myoclonic absences (1/22). FS typically clustered and were prolonged (<20 minutes) with (1) cyanosis, hypomotor, and vegetative semiology, sometimes unnoticed, followed by (2) tonic-vibratory and (3) (hemi)-clonic manifestations ± evolution to a bilateral tonic-clonic seizure. FS had posterior-temporal/occipital onset, slowly spreading and sometimes migrating between hemispheres. Brain MRI showed progressive parenchymal atrophy and restriction of the optic radiations.

Conclusions: developmental and epileptic encephalopathy has strikingly consistent electroclinical features, suggesting a global progressive brain dysfunction primarily affecting the temporo-occipital regions. Both uncontrolled epilepsy and developmental compromise contribute to the profound impairment (increasing risk of death) during early childhood, but stabilization occurs in late childhood.
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http://dx.doi.org/10.1212/WNL.0000000000006199DOI Listing
September 2018

Blood oxidative stress and metallothionein expression in Rett syndrome: Probing for markers.

World J Biol Psychiatry 2016 04 15;17(3):198-209. Epub 2015 Oct 15.

c DISTAV, Dipartimento Di Scienze Della Terra , Dell'ambiente E Della Vita, Università Di Genova , Genova , Italy .

Objectives: Oxidative stress seems to be involved in Rett syndrome (RTT). The aim of this study was to assess the antioxidant status in RTT children with MECP2 gene mutations with respect to healthy controls, and to explore novel blood antioxidant markers for RTT severity.

Methods: In erythrocytes from RTT females aged 2-14 years (n = 27) and age-matched controls (n = 27), we measured the levels of malonaldehyde and the activity of two antioxidant enzymes, Cu/Zn-superoxide dismutase and catalase, by spectrophotometric assays. In leukocytes, the expression of metallothioneins, the main non-enzymatic antioxidants, was assessed by real-time RT-PCR. In nine selected RTT children, methylome analysis was also performed.

Results: Blood of RTT patients showed increased lipid peroxidation and a dysregulated pattern of MT expression, while enzymatic activities did not change significantly with respect to controls. Moreover, we observed no epigenetic dysregulation in CpG-enriched promoter regions of the analysed genes but significant hypomethylation in the random loci.

Conclusions: As the haematic level of MT-1A directly correlates with the phenotype severity, this metallothionein can represent a marker for RTT severity. Moreover, the attempt to link the level of blood oxidative stress with MECP2 mutation and specific clinical features led us to draw some interesting conclusions.
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http://dx.doi.org/10.3109/15622975.2015.1077990DOI Listing
April 2016

Recent insights into genotype-phenotype relationships in patients with Rett syndrome using a fine grain scale.

Res Dev Disabil 2014 Nov 12;35(11):2976-86. Epub 2014 Aug 12.

Department of Psychology, Catholic University of the Sacred Heart, Largo Gemelli 1, 20123 Milano, Italy; Laboratory of Cellular Biochemistry and Molecular Biology-CRIBENS, Catholic University of the Sacred Heart, Piazza Buonarroti 30, 20145 Milano, Italy.

Mutations in MECP2 gene cause Rett syndrome (RTT), a neurodevelopmental disorder affecting around 1 in 10,000 female births. The clinical picture of RTT appears quite heterogeneous for each single feature. Mutations in MECP2 gene have been associated with the onset of RTT. The most known gene function consists of transcriptional repression of specific target genes, mainly by the binding of its methyl binding domain (MBD) to methylated CpG nucleotides and recruiting co-repressors and histone deacetylase binding to DNA by its transcription repressor domain (TRD). This study aimed at evaluating a cohort of 114 Rett syndrome (RTT) patients with a detailed scale measuring the different kinds of impairments produced by the syndrome. The sample included relatively large subsets of the most frequent mutations, so that genotype-phenotype correlations could be tested. Results revealed that frequent missense mutations showed a specific profile in different areas of impairment. The R306C mutation, considered as producing mild impairment, was associated to a moderate phenotype in which behavioural characteristics were mainly affected. A notable difference emerged by comparing mutations truncating the protein before and after the nuclear localization signal; such a difference concerned prevalently the motor-functional and autonomy skills of the patients, affecting the management of everyday activities.
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http://dx.doi.org/10.1016/j.ridd.2014.07.031DOI Listing
November 2014

Think about it: FMR1 gene mosaicism.

J Child Neurol 2014 Sep 23;29(9):NP74-7. Epub 2013 Sep 23.

Pediatric Clinic 1, Department of Pathophysiology and Transplantation, University of Milan Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy

Fragile X syndrome (FXS) is one of the most frequent causes of mental retardation, intellectual disability, and autism. Most cases are the result of an expansion of the CGG trinucleotide repeat in the 5' untranslated region of the FMR1 gene and the subsequent functional loss of the related protein. We describe the case of a 4-year-old boy who clinically presents mild psychomotor delay without any major clinical dysmorphisms. Molecular analysis of the FMR1 gene showed mosaicism in terms of size and methylation, with one normal and 1 fully mutated allele, which is very rare in this syndrome. Physicians should therefore consider a diagnosis of FXS even if the patient's phenotype is mild. Although rare, diagnosing this condition has important consequences for the patient's rehabilitation and the family planning of parents and relatives.
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http://dx.doi.org/10.1177/0883073813503187DOI Listing
September 2014

Juxtaposition of heterochromatic and euchromatic regions by chromosomal translocation mediates a heterochromatic long-range position effect associated with a severe neurological phenotype.

Mol Cytogenet 2012 Apr 4;5:16. Epub 2012 Apr 4.

Laboratory of Medical Cytogenetics and Molecular Genetics, Istituto Auxologico Italiano, Cusano Milanino 20095, Italy.

Background: The term "position effect" is used when the expression of a gene is deleteriously affected by an alteration in its chromosomal environment even though the integrity of the protein coding sequences is maintained. We describe a patient affected by epilepsy and severe neurodevelopment delay carrying a balanced translocation t(15;16)(p11.2;q12.1)dn that we assume caused a position effect as a result of the accidental juxtaposition of heterochromatin in the euchromatic region.

Results: FISH mapped the translocation breakpoints (bkps) to 15p11.2 within satellite III and the 16q12.1 euchromatic band within the ITFG1 gene. The expression of the genes located on both sides of the translocation were tested by means of real-time PCR and three, all located on der(16), were found to be variously perturbed: the euchromatic gene NETO2/BTCL2 was silenced, whereas VPS35 and SHCBP1, located within the major heterochromatic block of chromosome 16q11.2, were over-expressed. Pyrosequencing and chromatin immunoprecipitation of NETO2/BTCL2 and VPS35 confirmed the expression findings. Interphase FISH analysis showed that der(16) localised to regions occupied by the beta satellite heterochromatic blocks more frequently than der(15).

Conclusions: To the best of our knowledge, this is the first report of a heterochromatic position effect in humans caused by the juxtaposition of euchromatin/heterochromatin as a result of chromosomal rearrangement. The overall results are fully in keeping with the observations in Drosophila and suggest the occurrence of a human heterochromatin position effect associated with the nuclear repositioning of the der(16) and its causative role in the patient's syndromic phenotype.
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http://dx.doi.org/10.1186/1755-8166-5-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395859PMC
April 2012

Rett networked database: an integrated clinical and genetic network of Rett syndrome databases.

Hum Mutat 2012 Jul 13;33(7):1031-6. Epub 2012 Apr 13.

Medical Genetics, Department of Biotechnology, University of Siena, Viale Bracci 2, Siena, Italy.

Rett syndrome (RTT) is a neurodevelopmental disorder with one principal phenotype and several distinct, atypical variants (Zappella, early seizure onset and congenital variants). Mutations in MECP2 are found in most cases of classic RTT but at least two additional genes, CDKL5 and FOXG1, can underlie some (usually variant) cases. There is only limited correlation between genotype and phenotype. The Rett Networked Database (http://www.rettdatabasenetwork.org/) has been established to share clinical and genetic information. Through an "adaptor" process of data harmonization, a set of 293 clinical items and 16 genetic items was generated; 62 clinical and 7 genetic items constitute the core dataset; 23 clinical items contain longitudinal information. The database contains information on 1838 patients from 11 countries (December 2011), with or without mutations in known genes. These numbers can expand indefinitely. Data are entered by a clinician in each center who supervises accuracy. This network was constructed to make available pooled international data for the study of RTT natural history and genotype-phenotype correlation and to indicate the proportion of patients with specific clinical features and mutations. We expect that the network will serve for the recruitment of patients into clinical trials and for developing quality measures to drive up standards of medical management.
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http://dx.doi.org/10.1002/humu.22072DOI Listing
July 2012

Medical care of adolescents and women with Rett syndrome: an Italian study.

Am J Med Genet A 2012 Jan 2;158A(1):13-8. Epub 2011 Dec 2.

Neurology Unit, Epilepsy Center, University of Milan, Italy.

Rett syndrome (RTT) is a rare neurodevelopmental disorder, linked to MECP2 gene mutations in the majority of cases, which results in severe disability and is associated with several comorbidities. The clinical condition of RTT patients tends to stabilize over time, and prolonged survival has recently been demonstrated. However, limited information is available on the long-term course of older patients with RTT, especially among those in Southern Europe. The aim of our study is to evaluate the main clinical features and state of health of adult Italian patients with RTT and to present their evolution over time, identifying major clinical issues present at different ages. A total of 130 families of patients with RTT aged ≥14 years were asked to complete a questionnaire, 84 of which were returned (65%). Among the clinical characteristics of RTT, stereotypies and poor hand function and feeding ability remained stable over time, while nonverbal communication tended to improve. With regard to the main pathologies, sleep, behavioral, and autonomic disorders persisted into adulthood, while epilepsy improved and musculoskeletal problems worsened. In our sample, older patients with R294X and R133C mutations and with C-terminal deletions showed lower levels of clinical severity. The development of guidelines for the clinical management of patients with RTT will assist health care providers in dealing with the complex RTT phenotype. More extensive data about the long-term course of the condition could help in the design of programs for secondary prevention of disabilities for younger females affected by the syndrome.
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http://dx.doi.org/10.1002/ajmg.a.34367DOI Listing
January 2012

Epilepsy in Rett syndrome: clinical and genetic features.

Epilepsy Behav 2010 Nov 21;19(3):296-300. Epub 2010 Aug 21.

Department of Child Neuropsychiatry, Epilepsy Centre, G. Gaslini Institute, University of Genoa, Genoa, Italy.

Epilepsy often occurs in Rett syndrome and is considered a major problem. The aim of this study was to define the clinical features of epilepsy and the correlation between seizures and both genotype and clinical phenotype in the Rett population. One hundred sixty-five patients with Rett syndrome referred to four Italian centers were recruited. All patients underwent video/EEG monitoring and molecular analysis of the MECP2 gene or, in negative cases, of the CDKL5 and FOXG1 genes. The frequency of epilepsy was 79%. Drug-resistant epilepsy occurred in 30% of all our patients with Rett syndrome and in 38% of those with epilepsy. Our findings demonstrate that epilepsy differs among the various phenotypes and genotypes with respect to age at onset, drug responsiveness, and seizure semiology. The Hanefeld and preserved speech variants represent the extremes of the range of severity of epilepsy: the preserved speech variant is characterized by the mildest epileptic phenotype as epilepsy is much less frequent, starts later, and is less drug resistant than what is observed in the other phenotypes. Another important finding is that seizure onset before 1 year of age and daily frequency are risk factors for drug resistance. Thus, this study should help clinicians provide better clinical counseling to the families of patients with Rett syndrome.
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http://dx.doi.org/10.1016/j.yebeh.2010.06.051DOI Listing
November 2010

Mutations in the small GTPase gene RAB39B are responsible for X-linked mental retardation associated with autism, epilepsy, and macrocephaly.

Am J Hum Genet 2010 Feb;86(2):185-95

Dulbecco Telethon Institute at Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy.

Human Mental Retardation (MR) is a common and highly heterogeneous pediatric disorder affecting around 3% of the general population; at least 215 X-linked MR (XLMR) conditions have been described, and mutations have been identified in 83 different genes, encoding proteins with a variety of function, such as chromatin remodeling, synaptic function, and intracellular trafficking. The small GTPases of the RAB family, which play an essential role in intracellular vesicular trafficking, have been shown to be involved in MR. We report here the identification of mutations in the small GTPase RAB39B gene in two male patients. One mutation in family X (D-23) introduced a stop codon seven amino acids after the start codon (c.21C > A; p.Y7X). A second mutation, in the MRX72 family, altered the 5' splice site (c.215+1G > A) and normal splicing. Neither instance produced a protein. Mutations segregate with the disease in the families, and in some family members intellectual disabilities were associated with autism spectrum disorder, epileptic seizures, and macrocephaly. We show that RAB39B, a novel RAB GTPase of unknown function, is a neuronal-specific protein that is localized to the Golgi compartment. Its downregulation leads to an alteration in the number and morphology of neurite growth cones and a significant reduction in presynaptic buttons, suggesting that RAB39B is required for synapse formation and maintenance. Our results demonstrate developmental and functional neuronal alteration as a consequence of downregulation of RAB39B and emphasize the critical role of vesicular trafficking in the development of neurons and human intellectual abilities.
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http://dx.doi.org/10.1016/j.ajhg.2010.01.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2820185PMC
February 2010

Evaluation of autism traits in Angelman syndrome: a resource to unfold autism genes.

Neurogenetics 2007 Aug 6;8(3):169-78. Epub 2007 Apr 6.

Clinic of Medical Genetics, IRCCS Istituto Auxologico Italiano, Milan, Italy.

Linkage and cytogenetics studies have found the Angelman syndrome (AS) chromosomal region to be of relevance to autism disorder (AD) or autism spectrum disorder (ASD). Autism is considered part of the behavioural phenotype in AS based on formal autism assessments (autism diagnostic interview-revised [ADI-R] and autism diagnostic observation schedule [ADOS]), which have mainly addressed the deleted AS group. We explored 23 AS patients including all genetic subtypes and made a co-morbid diagnosis of AD/ASD in 14/23 (61%), which does not include 4 cases classified within the broader autism spectrum disorder (bASD). Deletions accounted for the main fraction (35%), ubiquitin-protein ligase E3A (UBE3A) mutation represented 13%, imprinting defects and uniparental disomy 9 and 4%, respectively. UBE3A mutations due to lack of the homologous to the E6-associated protein carboxyl terminus domain (n = 3) were associated with the ASD, while more distal mutations (n = 3) seem to escape from a co-morbid diagnosis of autism/autism spectrum. Differences in severity of autistic features were seen across subtypes of AS, with some behavioural features being unique to AS and some representing all forms of developmental disability. Autism signs (poor/lack of eye contact, showing, spontaneous initiation of joint attention, social quality of overtures [ADOS algorithm items for Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV)/International Statistical Classification of Diseases and Related Health Problems-10 (ICD-10) autism diagnosis belonging to the reciprocal social interaction domain]) discriminating all the co-morbid AS categories from non-autistic AS belonged to the social interaction domain. Impairments in the communication domain (gestures, pointing, use of another's body, frequency of vocalisation towards others [ADOS algorithm items for DSM-IV/ICD-10 autism diagnosis belonging to the communication domain]) justified classification of co-morbid AD/ASD vs the classification of less affected bASD. Evaluation of the behaviour domain suggested that repetitive sensory and motor behaviours correlate with a low developmental profile rather than being specific to autism.
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http://dx.doi.org/10.1007/s10048-007-0086-0DOI Listing
August 2007

A fluorescent method for detecting low-grade 11patUPD mosaicism in Beckwith-Wiedemann syndrome.

Mol Cell Probes 2003 Dec;17(6):295-9

Laboratory of Molecular Biology, Istituto Auxologico Italiano, Milan 20135, Italy.

The quantitative evaluation of mosaicism for uniparental disomy (UPD) involving a restricted chromosomal region requires the availability of a sensitive and reproducible method that is capable of detecting even a small percentage of disomic cells and avoiding false positive and false negative results. The occurrence of UPD is usually monitored by means of the parent-proband segregation analysis of microsatellites mapping to the target region. We here describe the quantitative blood cell evaluation of segmental mosaic UPD11, a marker of Beckwith-Wiedemann syndrome, by means of the segregation analysis of 11p15 microsatellites using both radioactive and fluorescence-based techniques. As the greater amplification efficiency of the shorter allele in heterozygous subjects may bias the correct evaluation of disomy, the mean short/long allele ratio was established at three loci of each of 30 normal heterozygous subjects, as well as the peak As/Al area in the presence of 50% of each allele. The interval was defined using a 5% level of significance. The results show that the fluorescence-based technique is superior to radioactivity in detecting the subtle allelic imbalances present in low-grade mosaicism conditions.
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http://dx.doi.org/10.1016/j.mcp.2003.07.002DOI Listing
December 2003