Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rett syndrome (RTT) is a neurodevelopmental disorder characterized by loss of acquired skills after a period of normal development in infant girls. The responsible gene, encoding methyl-CpG binding protein 2 (MeCP2), was recently discovered. Here we explore the spectrum of phenotypes resulting from MECP2 mutations. Both nonsense (R168X and R255X) and missense (R106W and R306C) mutations have been found, with multiple recurrences. R168X mutations were identified in six unrelated sporadic cases, as well as in two affected sisters and their normal mother. The missense mutations were de novo and affect conserved domains of MeCP2. All of the nucleotide substitutions involve C-->T transitions at CpG hotspots. A single nucleotide deletion, at codon 137, that creates a L138X stop codon within the methyl-binding domain was found in an individual with features of RTT and incontinentia pigmenti. An 806delG deletion causing a V288X stop in the transcription-repression domain was identified in a woman with motor-coordination problems, mild learning disability, and skewed X inactivation; in her sister and daughter, who were affected with classic RTT; and in her hemizygous son, who died from congenital encephalopathy. Thus, some males with RTT-causing MECP2 mutations may survive to birth, and female heterozygotes with favorably skewed X-inactivation patterns may have little or no involvement. Therefore, MECP2 mutations are not limited to RTT and may be implicated in a much broader phenotypic spectrum.
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PMID:Rett syndrome and beyond: recurrent spontaneous and familial MECP2 mutations at CpG hotspots. 1057 5

To study the clinical overlap between Rett (RTT) and Angelman syndromes (AS), we screened the MECP2 gene in a cohort of 78 patients diagnosed as possible AS but who showed a normal methylation pattern at the UBE3A locus. MECP2 missense (R106W, G428S), nonsense (R255X, R270X), and frameshift mutations (803 delG) were identified in 6/78 patients including 4/6 female cases consistent with RTT, one female case with progressive encephalopathy of neonatal onset, and one isolated male case with non-fatal, non-progressive encephalopathy of neonatal onset. This study shows that MECP2 mutations can account for a broad spectrum of clinical presentations and raises the difficult issue of the screening of the MECP2 gene in severe encephalopathy in both males and females.
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PMID:MECP2 mutation in non-fatal, non-progressive encephalopathy in a male. 1123 84

Rett syndrome, a neurodevelopmental disorder that is a leading cause of mental retardation in females, is caused by mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). MECP2 mutations have subsequently been identified in patients with a variety of clinical syndromes ranging from mild learning disability in females to severe mental retardation, seizures, ataxia, and sometimes neonatal encephalopathy in males. In classic Rett syndrome, genotype-phenotype correlation studies suggest that X chromosome inactivation patterns have a more prominent effect on clinical severity than the type of mutation. When the full range of phenotypes associated with MECP2 mutations is considered, however, the mutation type strongly affects disease severity. MeCP2 is a transcriptional repressor that binds to methylated CpG dinucleotides throughout the genome, and mutations in Rett syndrome patients are thought to result in at least a partial loss of function. Abnormal gene expression may thus underlie the phenotype. Discovering which genes are misregulated in the absence of functional MeCP2 is crucial for understanding the pathogenesis of this disorder and related syndromes.
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PMID:Molecular genetics of Rett syndrome and clinical spectrum of MECP2 mutations. 1126 31

The recent identification of mutations in the gene, MECP2, in girls with Rett syndrome (RS) firmly establishes the molecular genetic basis of this X-linked dominant disorder. This discovery, with ramifications far beyond establishing the gene for RS, represents a dramatic conclusion to an intensive, decade-long search. MECP2 encodes a methyl-CpG-binding protein (MeCP2) involved in transcriptional silencing of a yet to be defined number and type of genes. The clinical spectrum of resultant disorders extends well beyond RS. Indeed, the clinical phenotypes for MECP2 mutations range from mild disability in the mother of a girl with RS to rapidly progressive encephalopathy in her brother. Further, the recent identification of MECP2 mutations in boys with phenotypes quite different from RS adds yet another element to the mix. Within the classic RS group, clinical severity varies remarkably, depending at least in part on the degree of non-random X-inactivation. Those with clinical patterns in the border zones of RS remain to be examined fully for less severe mutational events. Further, the pathobiology of RS and the role of transcriptional silencing as a disease-producing mechanism could be a prototype for other disorders of neurodevelopment. Thus, the identification of mutations in MECP2 creates completely new vistas as to fundamental neurobiologic processes, to disease mechanisms in the neurodevelopmental disabilities, and to potential new therapeutic strategies for RS and related disorders.
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PMID:Rett syndrome: clinical correlates of the newly discovered gene. 1173 73

Rett syndrome is a neurodevelopmental disorder characterized by cognitive and adaptive regression with autistic features, loss of acquired skills, and stereotypic hand movements that almost exclusively affects females. It is an X-linked dominant disorder, with presumed lethality in males. Nonetheless, there are a few descriptions of males suspected of having Rett syndrome. With the recent discovery that the MECP2 gene is responsible for most cases of Rett syndrome, it is possible to molecularly assess cases of affected males by direct sequencing analysis. We describe an Israeli family consisting of a female having classic Rett syndrome and a male sibling with severe neonatal encephalopathy. Molecular analysis revealed that both sister and brother have the same MECP2 gene mutation; however, their mother does not. This case, as well as other published studies of males with MECP2 mutations, reveals that the clinical manifestations in viable males vary from neonates with severe encephalopathy to adults with mental retardation and demonstrate genotype-phenotype correlations.
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PMID:Rett syndrome: clinical manifestations in males with MECP2 mutations. 1191 64

We describe the clinical and neuropathological presentation of a male with an MECP2 mutation whose sister has Rett syndrome (RS). He presented with severe neonatal encephalopathy and died at the age of 13 months. Mutation analysis of the MECP2 gene demonstrated a 488 - 489 del mutation in his and his sister's copies of the gene. Post mortem examination revealed bilateral polymicrogyria in the perisylvian region. This malformation was visibly more severe than previously described in females with RS and another male with an MECP2 mutation. As bilateral polymicrogyria was described in congenital perisylvian syndrome, the presented patient could be regarded as having suffered from a severe form of this syndrome. We conclude that MECP2 screening should be considered in males with severe neonatal encephalopathy and in males and females with a bilateral polymicrogyria syndrome.
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PMID:MECP2 mutation in a boy with severe neonatal encephalopathy: clinical, neuropathological and molecular findings. 1193 Feb 74

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the MECP2 gene, with apparent lethality in male embryos. However, recent studies indicate that mutations in the MECP2 gene can cause congenital encephalopathy, an Angelman-like phenotype and even nonspecific mental retardation in males. We report on a 10-year-old boy with moderate mental retardation, hypotonia, obesity and gynaecomastia and a de novo 2-bp deletion in the MECP2 gene that resulted in a frameshift and premature stop codon. As some of the clinical features were suggestive of the Prader-Willi syndrome, it might be worthwhile screening for MECP2 mutations in patients with an atypical Prader-Willi phenotype but without the characteristic abnormalities on chromosome 15q. This report contributes to the phenotypic knowledge of male patients with MECP2 mutations. Moreover, this is the first reported male case of a de novo MECP2 mutation.
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PMID:De novo MECP2 frameshift mutation in a boy with moderate mental retardation, obesity and gynaecomastia. 1208 20

Although MECP2 was initially identified as the causative gene in classic Rett syndrome (RTT), the gene has now been implicated in several phenotypes that extend well beyond the clinically defined disorder. MECP2 mutations have been found in people with various disorders, including neonatal onset encephalopathy, X-linked recessive mental retardation (MRX), classic and atypical RTT, autism, and Angelman syndrome, as well as mildly affected females and normal carrier females. To make matters more complex, in approximately 20% of classic sporadic RTT cases and more than 50% of affected sister pairs, no mutation in MECP2 has been found. X-chromosome inactivation patterns can clearly affect the phenotypic expression in females, while the effect of the type and position of the mutation is more apparent in the broader phenotype than in RTT. Both males and females are at risk, although an excess of paternally derived mutations are found in most cases of classic RTT. Thus, because of the range of disparate phenotypes, the gene may account for a relatively large portion of mental retardation in the population.
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PMID:The phenotypic consequences of MECP2 mutations extend beyond Rett syndrome. 1211 34

Mutations in the MECP2 (Methyl-CpG-binding protein) gene recently have been reported to cause Rett syndrome (RTT), an X-linked progressive encephalopathy. We have collected the results of MECP2 analysis conducted in four laboratories in France. A total of 301 RTT alleles have been analyzed, demonstrating a total of 69 different mutations so far observed and accounting for 64% of MECP2 genes in RTT patients living in France. R168X (11.5%) is the most common of MECP2 mutations, followed by R255X (10.9%), R270X (10.5%), T158M (7.8%), and R306C (6.8%). Only 10 mutations had a relative frequency > 2%. A total of 59 mutations were found in a small number of RTT alleles (from 1 to 2). These data demonstrate the high allelic heterogeneity of RTT in France and provide information relevant to the development of strategies for molecular diagnosis and genetic counseling in RTT families.
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PMID:Spectrum of MECP2 mutations in Rett syndrome. 1218 70

Rett syndrome (RTT) is classically defined by meeting certain clinical diagnostic criteria. It affects mostly females, and one possible pathogenic mechanism was considered to involve mitochondrial function. This was based on the finding of ultrastructural alterations in the mitochondria and decreased respiratory chain enzyme activity. However, the principal etiology of RTT has since been found to be mutations in the MECP2 gene, which is located on the X chromosome. Molecular analysis has allowed the phenotype of MECP2 mutations to be broadened beyond RTT to include girls who have mild mental retardation, autism, and an Angelman syndrome phenotype, as well as males with severe encephalopathy. We present a girl with a previously described mutation in the MECP2 gene whose phenotype is of atypical RTT. She presented with hypotonia and developmental delay in infancy without a clear period of normal development. As part of her evaluation for hypotonia, a muscle biopsy and respiratory chain enzyme analysis showed a slight decrease in respiratory chain enzyme activity consistent with previous reports. This report supports broadening the phenotype of patients who should be considered for MECP2 mutation analysis to include cases of developmental delay and hypotonia without evidence of an initial period of normal development. Furthermore, it supports the hypothesis of an underlying secondary defect in energy metabolism contributing to the pathogenesis of RTT.
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PMID:Infantile hypotonia as a presentation of Rett syndrome. 1221 Mar 19


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