Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Characteristics are hypotonia, problems with feeding and thriving in the neonate and infant, later hyperphagia and severe obesity. Other findings are dysmorphic traits, hypogonadism, short stature, developmental delay, mental retardation and behavioural problems. Diabetes mellitus (NIDDM) is frequent in adults. Treatment is symptomatic. Prognosis is determined by obesity. PWS occurs almost always sporadically and is found in all ethnic groups and in both sexes. The epidemiology of PWS in Denmark is unknown. In 95% of cases with PWS cytogenetic and molecular genetic investigations show either deletion of the paternal chromosome 15q11q13 or uniparental maternal disomy of chromosome 15. Since 1992 150 bloodsamples of patients suspected for PWS have been investigated by cytogenetic and molecular genetic techniques at the John F. Kennedy Institute, DK-2600 Glostrup; deletion of the paternal chromosome 15 was found in 15 and uniparental maternal disomy of chromosome 15 in eight cases.
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PMID:[Prader-Willi syndrome--clinical picture and genetics]. 772 49

Prader-(Labhart-)Willi syndrome (PWS) is characterized by infantile hypotonia, early childhood obesity, mental deficiency, short stature, small hands and feet and hypogonadism. In 70% of the cases this syndrome is associated with a defect of chromosome 15 at 15q11-q13, close to the location of the 7B2 gene (15q13-q14). The majority of the remaining PWS patients display maternal uniparental disomy on chromosome 15. Since the 7B2 gene products are expressed in neuroendocrine cells that are probably affected in PWS, e.g. by a pleiotrophic influence of the neighboring deletion, the presence of 7B2 was studied in the supraoptic and paraventricular nucleus of the hypothalamus of five subjects clinically diagnosed as PWS patients using five antibodies against various parts of the 7B2 precursor polypeptide. Three of the five PWS patients studied showed no reaction to the 7B2 antibody MON-102, whereas all 30 control patients did. However, one of the three MON-102 non-reacting PWS patients reacted to other 7B2 antibodies. In conclusion, the vanishing of 7B2 gene products is not obligatory for PWS, possibly due to the variable genetic background of PWS patients. However, in most patients there is a clear modification of 7B2 expression, pointing to altered neuroendocrine functions.
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PMID:Differential expression of the neuroendocrine polypeptide 7B2 in hypothalami of Prader-(Labhart)-Willi syndrome patients. 782 Jun 29

Eating and sleeping problems have a high prevalence in mental retardation in general, but are also discussed as characteristic in some genetically determined disorders. A comparative analysis of eating and sleeping behaviours in 28 Prader-Willi- and 32 Williams-Beuren syndrome children by psychometric instruments confirms excessive food-seeking behaviours in PWS and selective food refusal in WBS as specific problems. In both syndromes, however, there is considerable individual variability in these symptoms.
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PMID:Specific eating and sleeping problems in Prader-Willi and Williams-Beuren syndrome. 873 69

The most common of the heterogeneous group of the extra structurally abnormal chromosomes (ESACs) is the inv dup(15), whose presence results in tetrasomy 15p and partial tetrasomy 15q. Inv dup(15), containing the Prader-Willi/Angelman syndrome (PWS/AS) region, are constantly associated with phenotypic abnormalities and mental retardation. We report on four additional patients with inv dup(15), whose behavioral pattern, and neurologic and physical findings further delineate the phenotype of this neurogenetic syndrome. We also provide FISH analyses on chromosomes of the observed ESACs and discuss the role of a number of genes located within the tetrasomic region.
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PMID:The inv dup(15) syndrome: a clinically recognizable syndrome with altered behavior, mental retardation, and epilepsy. 910 4

Duplications of chromosome region 15q11q13 often occur as a supernumerary chromosome 15. Less frequently they occur as interstitial duplications [dup(15)]. We describe the clinical and molecular characteristics of three patients with de novo dup(15). The patients, two males and one female (ages 3-21 years), had nonspecific findings that included autistic behavior, hypotonia, and variable degrees of mental retardation. The extent, orientation, and parental origin of the duplications were assessed by fluorescent in situ hybridization, microsatellite analyses, and methylation status at D15S63. Two patients had large direct duplications of 15q11q13 [dir dup(15)(q11q13)] that extended through the entire Angelman syndrome/Prader-Willi syndrome (AS/PWS) chromosomal region. Their proximal and distal breaks, at D15S541 or D15S9 and between D15S12 and D15S24, respectively, were comparable to those found in the common AS/PWS deletions. This suggests that duplications and deletions may be the reciprocal product of an unequal recombination event. These two duplications were maternally derived, but the origin of the chromatids involved in the unequal crossing over in meiosis differs. In one patient, the duplication originated from two different maternal chromosomes, while in the other patient it arose from the same maternal chromosome. The third patient had a much smaller duplication that involved only D15S11 and parental origin could not be determined. There was no obvious correlation between phenotype and extent of the duplication in these patients.
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PMID:Interstitial duplications of chromosome region 15q11q13: clinical and molecular characterization. 974 64

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by mental retardation, speech impairment, ataxia, and happy disposition with frequent smiling. AS results from the loss of expression of a maternal imprinted gene, UBE3A, mapped within 15q11-q13 region, due to different mechanisms: maternal deletion, paternal UPD, imprinting center mutation, and UBE3A mutation. Deletion AS patients may exhibit hypopigmentation of skin, eye, and hair correlating with deletion of P gene localized in the distal part of Prader-Willi (PWS)/AS region. Our patient presented developmental delay, severe mental retardation, absence of speech, outbursts of laughter, microcephaly, ataxia, hyperactivity, seizures, white skin, no retinal pigmentation, and gold yellow hair. His parents were of African ancestry. The SNURF-SNRPN methylation analysis confirmed AS diagnosis and microsatellite studies disclosed deletion with breakpoints in BP2 and BP3. All of the 25 exons and flanking introns of the P gene of the patient, his father, and mother were investigated. The patient is hemizygous for the deleted exon 7 of the P gene derived from his father who is a carrier of the deleted allele. Our patient manifests OCA2 associated with AS due to the loss of the maternal chromosome 15 with the normal P allele, and the paternal deletion in the P gene. As various degrees of hypopigmentation are associated with PWS and AS patients, the study of the P gene in a hemizygous state could contribute to the understanding of its effect on human pigmentation during development and to disclose the presence of modifier pigmentation gene(s) in the PWS/AS region.
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PMID:Angelman syndrome associated with oculocutaneous albinism due to an intragenic deletion of the P gene. 1274 60

The association of obesity, phenotypic abnormalities and mental retardation characterizes syndromic obesity. Its most common form is the Prader-Willi syndrome (PWS-- neonatal hypotonia, poor sucking, delayed psychomotor development, hyperphagia, severe obesity, short stature, small hands and feet, hypogonadism, mild to moderate mental retardation and behavioral disorders). A PWS-like phenotype has been described in patients with chromosome abnormalities involving the chromosome region 6q16.2 that includes the SIM1 gene. Herein we report cytogenetic and gene studies including a screening for the SIM1 gene deletion, performed on 87 patients with PWS-like phenotype, and describe the fifth case of syndromic obesity with an interstitial deletion of the chromosome segment 6q16-q21 and suggest that mutational analysis and further studies of the parental origin of chromosome alterations of 6q16.2 in patients with and without PWS-like phenotype are needed to evaluate possible imprinting effects of SIM1 gene and establish the contribution that alterations in this gene makes to the etiology of syndromic and non-syndromic obesity.
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PMID:A new case of interstitial 6q16.2 deletion in a patient with Prader-Willi-like phenotype and investigation of SIM1 gene deletion in 87 patients with syndromic obesity. 1682 51

Two common classes of deletions are described in the literature in individuals with Prader-Willi/Angelman syndrome (PWS/AS): one between breakpoint 1 (BP1) to BP3 and the other between BP2 to BP3 of the PWS/AS critical region on chromosome 15q11-->q13. We present here a novel observation of an approximately 253-kb deletion between BP1 and BP2 on 15q11.2, in a 3(1/2)-year-old boy, who was referred to us with a clinical suspicion of having Angelman syndrome and presenting with mental retardation, neurological disorder, developmental delay and speech impairment. Karyotype and FISH results were found to be normal. The microdeletion between BP1 and BP2 includes four genes - NIPA1, NIPA2, CYFIP1 and TUBGCP5 which was detected by a high-resolution oligonucleotide array-CGH that was further validated by a Multiplex Ligation-dependent Probe Amplification (MLPA) assay. The same deletion was observed in the father who presented with similar but relatively milder clinical features as compared to the affected son. Methylation studies by methylation-specific MLPA (MS-MLPA) of the SNRPN imprinting center (IC) showed a normal imprinting pattern, both in the patient and the father. To our knowledge a microdeletion limited only to the BP1-BP2 region has not yet been reported. The familial genetic alteration together with the striking clinical presentation in this study are interesting, but from our single case study it is difficult to suggest if the deletion is causative of some of the abnormal features or if it is a normal variant. The study however further strengthens the fact that genome-wide analysis by array CGH in individuals with developmental delay and mental retardation is very useful in detecting such hidden interstitial chromosomal rearrangements.
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PMID:Detection of a novel familial deletion of four genes between BP1 and BP2 of the Prader-Willi/Angelman syndrome critical region by oligo-array CGH in a child with neurological disorder and speech impairment. 1726 93

Prader-Willi syndrome (PWS [MIM 176270]) is a neurogenetic disorder characterized by decreased fetal activity, muscular hypotonia, failure to thrive, short stature, obesity, mental retardation, and hypogonadotropic hypogonadism. It is caused by the loss of function of one or more imprinted, paternally expressed genes on the proximal long arm of chromosome 15. Several potential PWS mouse models involving the orthologous region on chromosome 7C exist. Based on the analysis of deletions in the mouse and gene expression in PWS patients with chromosomal translocations, a critical region (PWScr) for neonatal lethality, failure to thrive, and growth retardation was narrowed to the locus containing a cluster of neuronally expressed MBII-85 small nucleolar RNA (snoRNA) genes. Here, we report the deletion of PWScr. Mice carrying the maternally inherited allele (PWScr(m-/p+)) are indistinguishable from wild-type littermates. All those with the paternally inherited allele (PWScr(m+/p-)) consistently display postnatal growth retardation, with about 15% postnatal lethality in C57BL/6, but not FVB/N crosses. This is the first example in a multicellular organism of genetic deletion of a C/D box snoRNA gene resulting in a pronounced phenotype.
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PMID:Deletion of the MBII-85 snoRNA gene cluster in mice results in postnatal growth retardation. 1816 85