Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

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

Mutations in the MECP2 (methyl-CpG-binding protein 2) gene are known to cause Rett syndrome, a well-known and clinically defined neurodevelopmental disorder. Rett syndrome occurs almost exclusively in females and for a long time was thought to be an X-linked dominant condition lethal in hemizygous males. Since the discovery of the MECP2 gene as the cause of Rett syndrome in 1999, MECP2 mutations have, however, also been reported in males. These males phenotypically have classical Rett syndrome when the mutation arises as somatic mosaicism or when they have an extra X chromosome. In all other cases, males with MECP2 mutations show diverse phenotypes different from classical Rett syndrome. The spectrum ranges from severe congenital encephalopathy, mental retardation with various neurological symptoms, occasionally in association with psychiatric illness, to mild mental retardation only. We present a 21-year-old male with severe mental retardation, spastic tetraplegia, dystonia, apraxia and neurogenic scoliosis. A history of early hypotonia evolving into severe spasticity, slowing of head growth, breathing irregularities and good visual interactive behaviour were highly suggestive of Rett syndrome. He has a de novo missense mutation in exon 3 of the MECP2 gene (P225L). The clinical spectrum and molecular findings in males with MECP2 mutations are reviewed.
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PMID:Neurodevelopmental disorders in males related to the gene causing Rett syndrome in females (MECP2). 1261 69

We describe a clinical profile of a male with Rett syndrome who presented initially with significant axial and peripheral hypotonia, head and truncal titubation and global delay. He is non-ambulatory, lost the few words he had learned and gradually developed hand stereotypes, breathing difficulties, seizures, scoliosis and has osteoporosis sleep problems and sludging in his gall bladder. Prior to diagnosis he underwent comprehensive neurological, metabolic and genetic investigations. After his older sister was diagnosed with atypical Rett syndrome; MECP2 mutation studies on him revealed a pathogenic mutation. His mother is a Rett carrier with a skewed inactivation of chromosome X. Clinical signs and symptoms required to meet the criteria for diagnosis of Rett syndrome have gradually evolved over time. This case demonstrates an unusual family history for Rett syndrome and alerts readers to the utility of screening males for Rett syndrome.
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PMID:Clinical profile of a male with Rett syndrome. 1618 90

A 20-year-old female with an established diagnosis of Rett syndrome was found dead in bed. There had been no history of recent deterioration in health and at autopsy no acute lesions were found. There was no evidence of trauma. Toxicological analysis of blood revealed therapeutic levels of carbamazepine and clonazepam. Death was attributed to the complications of Rett syndrome, an uncommon developmental disorder characterized by autistic type behaviour, hypotonia, stereotyped movements, seizures and growth failure, caused by mutations in the MECP2 gene on the X chromosome. Establishing the precise cause of sudden death in individuals with Rett syndrome may be difficult as epilepsy, defective autonomic nervous system control and cardiac arrhythmias may relate more to functional problems rather than to defects that can be demonstrated at autopsy. Thus, although there are a variety of well-documented underlying mechanisms that may cause sudden death in this condition, determining the exact sequence of events in an unwitnessed death may be more by inference and elimination, given the absence of pathognomonic and acute lethal lesions that are able to be found histopathologically. 'Complications of Rett syndrome' may, therefore, be the most accurate designation when individuals with this condition are found unexpectedly dead and no anatomical cause of death can be identified at autopsy.
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PMID:Forensic issues and possible mechanisms of sudden death in Rett syndrome. 1626 20

Pitt-Hopkins syndrome is a rare dysmorphic mental retardation syndrome marked by daytime spells of overbreathing interrupted by apnoea. The dysmorphism consists of a large beaked nose, cup-shaped ears with broad helices, a wide mouth, Cupid's bow upper lip, wide and shallow palate and broad or clubbed fingertips. The four patients described so far have been sporadic and represented both sexes. In addition, a pair of sibs with atypical features has been reported as possible Pitt-Hopkins syndrome cases. We describe two unrelated Pitt-Hopkins syndrome patients in order to further define the phenotype. In addition to severe developmental retardation, hypotonia, postnatal growth retardation, microcephaly, abnormal breathing and characteristic dysmorphic features, both had epilepsy and intestinal problems with severe constipation in one and Hirschsprung disease in the other. Other abnormalities were hypopigmented skin macules in one and high-grade myopia in the other. Both had unusual frontal slow-and-sharp-wave discharges on electroencephalography. Magnetic resonance imaging in both showed a similar hypoplastic corpus callosum with missing rostrum and posterior part of the splenium and bulbous caudate nuclei bulging towards the frontal horns. Chromosomal analysis and subtelomere fluorescence in-situ hybridization studies were normal. No mutations were found in the MECP2 or ZFHX1B genes. Extensive metabolic and mitochondrial screens were normal. The electroencephalography and brain magnetic resonance imaging findings appear to be further diagnostic signs in Pitt-Hopkins syndrome, which is also one of the syndromes associated with Hirschsprung disease.
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PMID:Pitt-Hopkins syndrome in two patients and further definition of the phenotype. 1653 28

Spinal muscular atrophy (SMA) is a neuromuscular autosomal recessive disease characterized by progressive muscle weakness and atrophy combined with motor neuron degeneration caused by mutations in the SMN 1 gene locus (5q11.2-13.2). Rett syndrome (RS) is an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2 (Xq28) and characterized by normal development until 6-12 months of age, followed by regression with loss of acquired skills, gradual onset of microcephaly, stereotypic hand movements and psychomotor delay. We report a 6-year-old girl who, at 2 years of age, presented with hypotonia, psychomotor delay, amyotrophy and areflexia of the lower extremities. Molecular DNA analysis (PCR-RFLP's) for SMA type II revealed that both exons 7 and 8 of SMN 1 gene were deleted. Over the past 4 years, onset of stereotypic hand-washing movements, epileptic seizures, microcephaly, hyperventilation/breath-holding attacks and severe psychomotor delay raised the suspicion of the coexistence of RS. DNA analysis (DGGE and sequencing) identified the hotspot missense mutation R306C (c.916C>T) in exon 4 of the MECP2 gene. The coinheritance of SMA and RS, two rare monogenic syndromes in the same patient, has not been previously reported. Thorough clinical evaluation in combination with DNA analysis, allowed accurate diagnosis, providing valuable information for the genetic counseling of the family.
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PMID:Coinheritance of mutated SMN1 and MECP2 genes in a child with phenotypic features of spinal muscular atrophy (SMA) type II and Rett syndrome. 1727 11

Non-mosaic males with a 46,XY karyotype and a MECP2 null mutation display a phenotype of severe neonatal-onset encephalopathy that is distinctly different from Rett syndrome (RTT). To increase awareness of this rare disorder, we are reporting novel findings in a sporadic case, compare them to 16 previously reported cases and establish salient criteria for clinical diagnosis. The proband suffered from general hypotonia and hypoxia caused by hypoventilation and irregular breathing. He developed abnormal movements, seizures and electroencephalogram abnormalities. He failed to thrive and to reach any motor milestones and died at 15 months from central respiratory failure without a diagnosis. In a muscle biopsy, type II fibers were reduced in diameter, indicating central hypoxia. At autopsy, the brain was small with disproportionate reduction of the frontal and temporal lobes. Synaptophysin staining of synaptic vesicles was greatly reduced in cerebellar and spinal cord sections. Analysis of Golgi-stained pyramidal neurons from cortical layers III and V of the frontal and temporal lobes revealed drastically diminished dendritic trees. Post-mortem MECP2 mutation analysis on DNA and RNA from fibroblasts revealed a novel de novo 9-nucleotide deletion including the intron 3/exon 4 splice junction. The two nucleotides flanking the deletion form a new splice site, and the aberrantly spliced transcript lacks seven nucleotides (r.378_384delTCCCCAG), causing a frameshift and premature termination codon (p.I126fsX11). Males with congenital encephalopathy, not females with RTT, represent the true human counterpart for the commonly studied Mecp2-/y mouse model and provide unique insight into the mechanisms of MeCP2 deficiency.
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PMID:Severe congenital encephalopathy caused by MECP2 null mutations in males: central hypoxia and reduced neuronal dendritic structure. 1847

Xq28 duplications encompassing MECP2 have been described in male patients with a severe neurodevelopmental disorder associated with hypotonia and spasticity, severe learning disability and recurrent pneumonia. We identified an Xq28 duplication in three families where several male patients had presented with intestinal pseudo-obstruction or bladder distension. The affected boys had similar dysmorphic facial appearances. Subsequently, we ascertained seven further families where the proband presented with similar features. We demonstrated duplications of the Xq28 region in five of these additional families. In addition to MECP2, these duplications encompassed several other genes already known to be associated with diseases including SLC6A8, L1CAM and Filamin A (FLNA). The two remaining families were shown to have intragenic duplications of FLNA only. We discuss which elements of the Xq28 duplication phenotype may be associated with the various genes in the duplication. We propose that duplication of FLNA may contribute to the bowel and bladder phenotype seen in these seven families.
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PMID:Xq28 duplication presenting with intestinal and bladder dysfunction and a distinctive facial appearance. 1885 60

Duplications in Xq28 involving MECP2 have been described in patients with severe mental retardation, infantile hypotonia, progressive spasticity, and recurrent infections. However, it is not yet clear to what extent these and accompanying symptoms may vary. In addition, the frequency of Xq28 duplications including MECP2 has yet to be determined in patients with unexplained X-linked mental retardation and (fe)males with severe encephalopathy. In this study, we used multiplex ligation-dependent probe amplification to screen Xq28 including MECP2 for deletions and duplications in these patient cohorts. In the group of 283 patients with X-linked mental retardation, we identified three Xq28 duplications including MECP2, which suggests that approximately 1% of unexplained X-linked mental retardation may be caused by MECP2 duplications. In addition, we found three additional MECP2 duplications in 134 male patients with mental retardation and severe, mostly progressive, neurological symptoms, indicating that the mutation frequency could be as high as 2% in this group of patients. In 329 female patients, no Xq28 duplications were detected. In total, we assessed 13 male patients with a MECP2 duplication from six unrelated families. Moderate to severe mental retardation and childhood hypotonia was noted in all patients. The majority of the patients also presented with absent speech, seizures, and progressive spasticity as well as ataxia or an ataxic gait and cerebral atrophy, two previously unreported symptoms. We propose to implement DNA copy number testing for MECP2 in the current diagnostic testing in all males with moderate to severe mental retardation accompanied by (progressive) neurological symptoms.
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PMID:Structural variation in Xq28: MECP2 duplications in 1% of patients with unexplained XLMR and in 2% of male patients with severe encephalopathy. 1898 75


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