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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angelman syndrome (AS) is characterized by severe psychomotor retardation, speech impairment, happy disposition with bursts of laughter, ataxia, convulsions, and some distinct physical anomalies. Correct diagnosis of AS is important because of its clinical implications, and once the disease is confirmed, familial genetic counseling becomes crucial. We evaluated 22 patients with a putative diagnosis of AS by both clinical and molecular cytogenetic analysis. A deletion of the region 15q11-13 could be identified cytogenetically in 11 cases by high-resolution technique (group I). Four additional cases were confirmed by fluorescence in situ hybridization (FISH) study with D15S11, SNRPN, D15S10, and GABRB 3 [Prader-Willi syndrome (PWS)/AS region probes] (group II). The common deletion of GABRB 3 was documented in those AS cases (n = 15) by FISH. The other 7 cases exhibited no deletion over 15q11-13 at either the cytogenetic or molecular level (group III). We compared the following associated neurological disorders: convulsions and abnormal EEG, microcephaly, sleep and behavior problems, brain anomalies proved by image studies, sexual precocity with pineal tumor among the three groups, as well as other clinical conditions including congenital heart disease, obesity, scoliosis, and hypopigmentation. In the present study, the differences in neurological and facial characteristics were not distinct among these groups. However, the associated conditions were more frequently observed in the patients with deletion than in those without deletion. The EEG features of AS appear to be less sufficient in helping identify patients at an early age before the clinical features become obvious. Therefore, a region involved in the major As phenotypes may contain only one or more tightly contiguous genes around the GABRB 3 locus, which may explain the clinical heterogeneity in AS.
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PMID:Angelman syndrome assessed by neurological and molecular cytogenetic investigations. 904 96

We had previously described a patient with an overgrowth syndrome and the chromosome constitution 45,XY,t(15q15q) (Wajntal et al., DNA Cell Biol 1993: 12: 227-231). Clinical reassessment and the use of molecular studies, including methylation analysis with an SNRPN probe, microsatellite analyses of D15S11, GABRB3 and D15S113 loci, and fluorescence in situ hybridization (FISH) using the SNRPN and GABRB3 probes, are consistent with a diagnosis of Angelman syndrome (AS) due to paternal isodisomy. This is the fourth report case of a translocation 15q15q with paternal uniparental disomy (UPD). Our findings suggest that some patients with clinical features of AS have hyperphagia and obesity with overgrowth, and that these features should not rule out a diagnosis of AS.
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PMID:Unusual clinical features in an Angelman syndrome patient with uniparental disomy due to a translocation 15q15q. 983 41

The clinical features of Angelman syndrome (AS) comprise severe mental retardation, postnatal microcephaly, macrostomia and prognathia, absence of speech, ataxia, and a happy disposition. We report on seven patients who lack most of these features, but presented with obesity, muscular hypotonia and mild mental retardation. Based on the latter findings, the patients were initially suspected of having Prader-Willi syndrome. DNA methylation analysis of SNRPN and D15S63, however, revealed an AS pattern, ie the maternal band was faint or absent. Cytogenetic studies and microsatellite analysis demonstrated apparently normal chromosomes 15 of biparental inheritance. We conclude that these patients have an imprinting defect and a previously unrecognised form of AS. The mild phenotype may be explained by an incomplete imprinting defect or by cellular mosaicism.
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PMID:A previously unrecognised phenotype characterised by obesity, muscular hypotonia, and ability to speak in patients with Angelman syndrome caused by an imprinting defect. 1085 4

Prader-Willi syndrome (PWS) is a neurobehavioural disorder characterized by neonatal respiratory depression, hypotonia and failure to thrive in infancy, followed by hyperphagia and obesity among other symptoms. PWS is caused by the loss of one or more paternally expressed genes on chromosome 15q11-q13, which can be due to gene deletions, maternal uniparental disomy or mutations disrupting the imprinting mechanism. Imprinted genes mapped to this region include SNRPN (refs 3,4), ZNF127 (ref. 5), IPW (ref. 6) and NDN (which encodes the DNA-binding protein necdin; refs 7,8,9,10). The mouse homologues of these genes map to mouse chromosome 7 in a region syntenic with human chromosome 15q11-q13 (refs 7,11). Imprinting of the human genes is under the control of an imprinting center (IC), a long-range, cis-acting element located in the 5' region of SNRPN (ref. 12). A related control element was isolated in the mouse Snrpn genomic region which, when deleted on the paternally inherited chromosome, resulted in the loss of expression of all four genes and early post-natal lethality. To determine the possible contribution of Ndn to the PWS phenotype, we generated Ndn mutant mice. Heterozygous mice inheriting the mutated maternal allele were indistinguishable from their wild-type littermates. Mice carrying a paternally inherited Ndn deletion allele demonstrated early post-natal lethality. This is the first example of a single gene being responsible for phenotypes associated with PWS.
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PMID:Disruption of the mouse necdin gene results in early post-natal lethality. 1050 1

Prader-Willi syndrome (PWS) is a neurogenetic disease characterized by infantile hypotonia, gonadal hypoplasia, obsessive behaviour and neonatal feeding difficulties followed by hyperphagia, leading to profound obesity. PWS is due to a lack of paternal genetic information at 15q11-q13 (ref. 2). Five imprinted, paternally expressed genes map to the PWS region, MKRN3 (ref. 3), NDN (ref. 4), NDNL1 (ref. 5), SNRPN (refs 6-8 ) and IPW (ref. 9), as well as two poorly characterized framents designated PAR-1 and PAR-5 (ref. 10). Imprinting of this region involves a bipartite 'imprinting centre' (IC), which overlaps SNRPN (refs 10,11). Deletion of the SNRPN promoter/exon 1 region (the PWS IC element) appears to impair the establishment of the paternal imprint in the male germ line and leads to PWS. Here we report a PWS family in which the father is mosaic for an IC deletion on his paternal chromosome. The deletion chromosome has acquired a maternal methylation imprint in his somatic cells. We have made identical findings in chimaeric mice generated from two independent embryonic stem (ES) cell lines harbouring a similar deletion. Our studies demonstrate that the PWS IC element is not only required for the establishment of the paternal imprint, but also for its postzygotic maintenance.
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PMID:De novo deletions of SNRPN exon 1 in early human and mouse embryos result in a paternal to maternal imprint switch. 1080 40

Loss of paternal gene expression at the imprinted domain on proximal human chromosome 15 causes Prader-Willi syndrome (PWS), a complex multiple-anomaly disorder involving variable mental retardation, hyperphasia leading to obesity and infantile hypotonia with failure to thrive. Although numerous paternally expressed transcripts have been identified that reside in the candidate region, the individual contributions to the development of PWS have not been firmly established. Recent studies of mouse models carrying a cytogenetic deletion suggest that paternal deficiency of the SNRPN-IPW interval is critical for perinatal lethality of potential relevance to PWS. Here we determined the allelic expression profiles of a total of 118 cDNA clones using monochromosomal hybrids retaining either a paternal or maternal human chromosome 15. Our results demonstrated a preponderance of unusual transcripts lacking protein-coding potential that were expressed exclusively from the paternal copy of the critical interval. This interval was also found to encompass a large direct repeat (DR) cluster displaying a potentially active chromatin conformation of paternal origin, as suggested by enhanced sensitivity to nuclease digestion. Database searches revealed an unexpected organization of tandemly repeated consensus elements, all of which possessed well-defined box C and D sequences characteristic of small nucleolar RNAs (snoRNAs). Southern blot analysis further demonstrated a considerable degree of phylogenetic conservation of the DR locus in the genomes of all mammalian species tested, but not in chicken, Xenopus and Drosophila. These findings imply a potential direct contribution of the DR locus, representing a cluster of multiple snoRNA genes, to certain phenotypic features of PWS.
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PMID:Large-scale evaluation of imprinting status in the Prader-Willi syndrome region: an imprinted direct repeat cluster resembling small nucleolar RNA genes. 1115 1

Here we describe the genetic studies performed in 53 patients with the suspected diagnosis of Prader-Willi syndrome (PWS). PWS is characterized by neonatal hypotonia, hypogonadism, delayed psychomotor development, hyperphagia, obesity, short stature, small hands and feet, learning disabilities, and obsessive-compulsive behavior. Through the methylation analysis of the SNRPN gene, microsatellite studies of loci mapped within and outside the PWS/AS region, and fluorescence in situ hybridization (FISH) study, we confirmed the diagnosis in 35 patients: 27 with a paternal deletion, and 8 with maternal uniparental disomy (UPD). The clinical comparisons between deleted and UPD patients indicated that there were no major phenotype differences, except for a lower birth length observed in the UPD children. Our sample was composed of more girls than boys; UPD patients were diagnosed earlier than the deleted cohort (2(10/12) s. 7(9/12) years); and, in the deleted group, the boys were diagnosed earlier than the girls (5(2/12) vs. 7(8/12) years, respectively).
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PMID:Prader-Willi syndrome: genetic tests and clinical findings. 1121 64

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are distinct human neurogenetic disorders; however, a clinical overlap between AS and PWS has been identified. We report on a further case of a patient showing the PWS phenotype with the AS molecular defect. Despite the PWS phenotype, the DNA methylation analysis of SNRPN revealed an AS pattern. Cytogenetic and FISH analysis showed normal chromosomes 15 and microsatellite analysis showed heterozygous loci inside and outside the 15q11-13 region. The presence of these atypical cases could be more frequent than previously expected and we reinforce that the DNA methylation analysis is important for the correct diagnosis of severe mental deficiency, congenital hypotonia and obesity.
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PMID:A further case of a Prader-Willi syndrome phenotype in a patient with Angelman syndrome molecular defect. 1256 98

Maternal uniparental disomy for chromosome 14 [upd(14)mat] is associated with a characteristic phenotype including pre- and postnatal growth retardation, muscular hypotonia, feeding problems, motor delay, small hands and feet, precocious puberty and truncal obesity. Patients with upd(14)mat show features overlapping with Prader-Willi syndrome (PWS) and are probably underdiagnosed. Maternal upd(14) is frequently described in carriers of a Robertsonian translocation involving chromosome 14, but is also found in patients with a normal karyotype. Based on the above mentioned criteria we have identified six patients with upd(14)mat including two patients with a normal karyotype, one patient with a de novo Robertsonian translocation (14;21), one patient with a familial Robertsonian translocation (13;14) and two patients with a marker chromosome. In addition, we analyzed a cohort of 33 patients with low birth weight, feeding difficulties and consecutive obesity in whom PWS had been excluded by methylation analysis of SNRPN. In four of these patients (12%) we detected upd(14)mat. For rapid testing of upd(14)mat we analyzed the methylation status of the imprinted MEG3 locus. In conclusion, we recommend considering upd(14)mat in patients with low birth weight, growth retardation, neonatal feeding problems, muscular hypotonia, motor delay, precocious puberty and truncal obesity as well as in patients with a PWS like phenotype presenting with low birth weight, feeding difficulties and obesity.
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PMID:Is there a higher incidence of maternal uniparental disomy 14 [upd(14)mat]? Detection of 10 new patients by methylation-specific PCR. 1690 36

Prader-Willi syndrome (PWS) is caused by loss of function of paternally expressed genes in the 15q11-q13 region and a paucity of data exists on transcriptome variation. To further characterize genetic alterations in this classic obesity syndrome using whole genome microarrays to analyze gene expression, microarray and quantitative RT-PCR analysis were performed using RNA isolated from lymphoblastoid cells from PWS male subjects (four with 15q11-q13 deletion and three with UPD) and three age and cognition matched nonsyndromic comparison males. Of more than 47,000 probes examined in the microarray, 23,383 were detectable and 323 had significantly different expression in the PWS lymphoblastoid cells relative to comparison cells, 14 of which were related to neurodevelopment and function. As expected, there was no evidence of expression of paternally expressed genes from the 15q11-q13 region (e.g., SNRPN) in the PWS cells. Alterations in expression of serotonin receptor genes (e.g., HTR2B) and genes involved in eating behavior and obesity (ADIPOR2, MC2R, HCRT, OXTR) were noted. Other genes of interest with reduced expression in PWS subjects included STAR (a key regulator of steroid synthesis) and SAG (an arrestin family member which desensitizes G-protein-coupled receptors). Quantitative RT-PCR for SAG, OXTR, STAR, HCRT, and HTR2B using RNA isolated from their lymphoblastoid cells and available brain tissue (frontal cortex) from separate individuals with PWS and control subjects and normalized to GAPD gene expression levels validated our microarray gene expression data. Our analysis identified previously unappreciated changes in gene expression which may contribute to the clinical manifestations seen in PWS.
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PMID:Whole genome microarray analysis of gene expression in Prader-Willi syndrome. 1723 94


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