OBJECTIVE: To conduct clinical and genetic analysis of two male patients with atypical Rett syndrome. METHODS: Collection of clinical data in the two patients and these parents; whole exome sequencing (WES) was used to detect the potential variants, which were verified by Sanger sequencing. X chromosome inactivation (XCI) detection is performed in the Patient 1's mother to detect the allelic expression difference of the MECP2 gene. RESULTS: Patient 1, a 5-year and 10-month-old boy, had mental disorders and mild intellectual disability (ID) (IQ: 54), whose mother had ID. Patient 2 was a 9-month and 18-day-old male presented with recurrent infections, respiratory insufficiency, hypotonia and global developmental delay. WES indentified a hemizygous mutation, c.499C>T (p.R167W), in the MECP2 gene in patient 1, which was inherited from his mother. The inactivation of X chromosome is skewed, and the expression ratio of wild-type and mutant MECP2 is 100%:0. Patient 2 was found a de novo splicing mutation, c.62+2_62+3del in the MECP2 gene. They were both reported pathogenic variant related to Rett syndrome. c.499C>T (p.R167W) was defined as likely pathogenic (PS1+PM2+PP3) and c.62+2_62+3del was pathogenic (PVS1+PM2+PM6) based on American College of Medical Genetics and Genomics standards and guidelines. CONCLUSION Both the two patients were diagnosed with rare male Rett syndrome, which had atypical clinical manifestations and large difference. Above foundings have revealed novel phenotypes in Chinese male patients with Rett syndrome.
Craniosynostoses ; Female ; Genetic Testing ; Humans ; Intellectual Disability/genetics* ; Male ; Methyl-CpG-Binding Protein 2/genetics* ; Mutation ; Phenotype ; Rett Syndrome/genetics*

OBJECTIVETo study the clinical features and mutations in methyl-CpG-binding protein 2 (MECP2) gene among children with classical Rett syndrome in China.

METHODSPCR and direct sequencing were employed to analyze the three exons of MECP2 gene in 9 children recently diagnosed with Rett syndrome and their parents.

RESULTSHeterozygous mutations were identified in 5 out of 9 patients, with a mutation rate of over 50%; there was one case of insert mutation (c.913insT) and 4 cases of missense mutation (exon 3: c.316C>T (R106W); exon 4: c.502C>T (R168X), c.808C>T (R270X), and c.1126C>T (P376S). A new mutation (c.913insT) was found. No mutations were detected in their parents. Two patients had MECP2 mutations in the transcriptional repression domain (TRD). They had almost lost language functions and were found to have significantly delayed development compared with other patients.

CONCLUSIONSMutations in MECP2 gene were detected in 5 confirmed cases of Rett syndrome, and most of them were on exon 4. Mutations in the TRD of MECP2 protein may affect the language ability and development in children with Rett syndrome.

Child, Preschool ; Female ; Humans ; Infant ; Language Development ; Methyl-CpG-Binding Protein 2 ; genetics ; Mutation ; Rett Syndrome ; genetics ; psychology

OBJECTIVERett syndrome (RTT) is a neurodevelopmental disorder that represents one of the most common genetic causes of mental retardation in girls. The aim of this study was to investigate the correlation between MECP2 genotype and phenotype and thereby not only to provide assistance for clinical care, but also facilitate clinical genetic counseling.

METHODIndividual phenotype characteristic and clinical severity of 126 children with RTT diagnosed by molecular genetic methods were evaluated by using scales of Kerr et al and Scala et al. Statistical package SPSS 12.0 was used for analyses of data. Since the majority of the data were not normally distributed, non-parametric tests were used. The Kruskal-Wallis test/Wilcoxon Mann-Whitney test was employed to compare total severity phenotype scores. The Fisher exact test was used for comparing rates. Statistical significance was set at P < 0.05.

RESULTThere were no significant differences in the average overall scores for RTT patients with mutations in the region of methyl-CpG-binding domain (MBD) compared with those mutations in the transcription repression domain (TRD) and C terminal segment (CTS), also patients with nonsense mutations compared with missense mutations, frameshift mutations and large deletions (P > 0.05). The RTT patients with nonsense mutations located in the region of MBD have more severe phenotype than those with missense mutations in the same region (P = 0.016). Among p.T158M, p.R168X, c.806delG and p.R255X, there were no significant differences in the average overall scores (P > 0.05), but there were significant differences in language skill (P = 0.028) and in language impairment rate at different level (P = 0.019).

CONCLUSIONThere are relationships between MECP2 genotype and phenotype:the RTT patients with nonsense mutations located in MBD tend to develop more severe phenotype;there are significant differences in language skill and language impairment rate in the groups with p.T158M, p.R168X, c.806del and p.R255X, which had higher frequency in children below five-years of age and the p.R168X present with most severe impairment.

Adolescent ; Child ; Child, Preschool ; Female ; Genotype ; Humans ; Infant ; Methyl-CpG-Binding Protein 2 ; genetics ; Phenotype ; Rett Syndrome ; genetics

Mutations of the X-linked methyl-CpG-binding protein 2 (MECP2) gene in humans are responsible for most cases of Rett syndrome (RTT), an X-linked progressive neurological disorder. While genome-wide screens in clinical trials have revealed several putative RTT-associated mutations in MECP2, their causal relevance regarding the functional regulation of MeCP2 at the etiologic sites at the protein level requires more evidence. In this study, we demonstrated that MeCP2 was dynamically modified by O-linked-β-N-acetylglucosamine (O-GlcNAc) at threonine 203 (T203), an etiologic site in RTT patients. Disruption of the O-GlcNAcylation of MeCP2 specifically at T203 impaired dendrite development and spine maturation in cultured hippocampal neurons, and disrupted neuronal migration, dendritic spine morphogenesis, and caused dysfunction of synaptic transmission in the developing and juvenile mouse cerebral cortex. Mechanistically, genetic disruption of O-GlcNAcylation at T203 on MeCP2 decreased the neuronal activity-induced induction of Bdnf transcription. Our study highlights the critical role of MeCP2 T203 O-GlcNAcylation in neural development and synaptic transmission potentially via brain-derived neurotrophic factor.
Animals ; Humans ; Methyl-CpG-Binding Protein 2/metabolism* ; Mice ; Neurodevelopmental Disorders/genetics* ; Rett Syndrome/genetics* ; Synaptic Transmission ; Threonine

PURPOSE: Rett syndrome is a severe neurodevelopmental disorder in females. Most have mutations in the methyl-CpG-binding protein 2 (MECP2) gene (80-90%). Epilepsy is a significant commonly accompanied feature in Rett syndrome. Our study was aimed at comprehensive analysis of genetic and clinical features in Rett syndrome patients, especially in regards to epileptic features. MATERIALS AND METHODS: We retrospectively reviewed 20 patients who were diagnosed with MECP2 mutations at Severance Children's Hospital between January 1995 and July 2010. All patients met clinical criteria for Rett syndrome. Evaluations included clinical features, epilepsy classification, electroencephalography analysis, and treatment of seizures. RESULTS: Ages ranged from 3.6 to 14.3 years (7.7+/-2.6). Fourteen different types of MECP2 mutations were found, including a novel in-frame mutation (1153-1188 del36). Fourteen of these patients (70.0%) had epilepsy, and the average age of seizure onset was 3.0+/-1.8 years. Epilepsy was diverse, including partial seizure in four patients (28.5%), secondarily generalized seizure in six (42.8%), generalized tonic seizure in two (14.3%), Lennox-Gastaut syndrome in one (7.1%), and myoclonic status in non-progressive encephalopathy in one (7.1%). Motor functions were delayed so that only 10 patients (50.0%) were able to walk independently: five (35.8%) in the epilepsy group and five (83.3%) in the non-epilepsy group. Average developmental scale was 33.5+/-32.8 in the epilepsy group and 44.4+/-21.2 in the non-epilepsy group. A clear genotype-phenotype correlation was not found. CONCLUSION: There is a tendency for more serious motor impairment and cognitive deterioration in Rett syndrome patients with epilepsy.
Adolescent ; Child ; Child, Preschool ; Epilepsy/*genetics/*pathology ; Female ; Genotype ; Humans ; Male ; Methyl-CpG-Binding Protein 2/*genetics ; Mutation ; Phenotype ; Retrospective Studies ; Rett Syndrome/*genetics/*pathology

OBJECTIVERett syndrome (RTT, MIM 312750) is a progressive neurodevelopmental disorder that affects females almost exclusively, caused by mutations in MECP2 gene on chromosome Xq28, with symptoms such as autism, severe mental deficiency, deceleration of head growth, ataxia, loss of purposeful hand function and characteristic stereotypic hand movements. Over 80% MECP2 mutations located in the exon 3 and exon 4 were confirmed by our work and large-scale studies. RTT is defined based on clinical presentation. It is difficult to diagnose in the early life without definite biochemical abnormality, but genetic test is helpful for this. The aim of this study was to investigate the feasibility and clinical significance of applying long range polymerase chain reaction (PCR) to RTT diagnosis and establish a simple, economic, efficient method of genetic diagnosis.

METHODGenomic DNA was extracted using standard procedures from the peripheral blood leukocytes of each patient. Long range polymerase chain reaction(PCR)and DNA direct sequencing were employed to analyze the exon 3 and 4 of MECP2 gene simultaneity in 40 patients with RTT. The PCR products were checked by using 1.5% agarose gel.

RESULTIn total, 18 different MECP2 mutations were identified in 33 of the 40 diagnosed sporadic female patients with RTT. Missense mutations were 16, followed by 14 nonsense mutations and 3 deletions. The 314 base pairs large deletion was identified. The p. T158M mutation (21%, 7/33) was the most common, followed in order of frequency by p. R255X (12%, 4/33), p. R168X and p. R106W (9%, 3/33) respectively, p. R270X and p. Y141X (6%, 2/33) respectively, p. R133C, p. D156H, p. P157L, p. P225R, p. Q244X, p. Q262X, p. R294X, p. R306C, P322L, c. 1005del G, c.1005-1318del 314 bp and c.1127-1179del 53 bp (3%, 1/33), respectively.

CONCLUSIONLong range PCR is a simple, economic, quick, precise method of genetic diagnosis and was able to find 83% MECP2 gene mutations in RTT patients in this study. It is helpful for RTT clinical diagnosis in early stage. On the other hand, it may detect recurrent mutations and large deletions at the same time.

Child ; Child, Preschool ; DNA ; analysis ; Exons ; genetics ; Female ; Humans ; Methyl-CpG-Binding Protein 2 ; genetics ; Mutation ; Polymerase Chain Reaction ; methods ; Rett Syndrome ; diagnosis ; genetics

Animals ; Humans ; Mental Retardation, X-Linked ; genetics ; Methyl-CpG-Binding Protein 2 ; chemistry ; genetics ; Receptors, N-Methyl-D-Aspartate ; physiology ; Rett Syndrome ; genetics

OBJECTIVETo identify the parental origin of methyl-CpG-binding protein 2 (MECP2) gene mutations in Chinese patients with Rett syndrome.

METHODSSingle nucleotide polymorphisms (SNPs) in intron 3 of the MECP2 gene were analyzed by PCR and sequencing in 115 patients with Rett syndrome. Then sequencing of the SNP region was performed for the fathers of the patients who had at least one SNP, to determine which allele was from the father. Then allele-specific PCR was performed and the products were sequenced to see whether the allele from father or mother harbored the mutation.

RESULTSSeventy-six of the 115 patients had at least one SNP. Three hot SNPs were found in these patients. They were: IVS3+22C >G, IVS3+266C >T and IVS3+683C>T. Among the 76 cases, 73 had a paternal origin of MECP2 mutations, and the other 3 had a maternal origin. There were multiple types of MECP2 mutation of the paternal origin, including 4 frame shift, 2 deletion and 67 point (56C >T, 6C >G, 2A >G, 2G >T and 1A >T) mutations. The mutation types of the 3 patients with maternal origin included 2 frame shift and 1 point (C >T) mutation.

CONCLUSIONIn Chinese RTT patients, the MECP2 mutations are mostly of paternal origin.

Base Sequence ; Child, Preschool ; DNA Mutational Analysis ; Fathers ; Female ; Humans ; Male ; Methyl-CpG-Binding Protein 2 ; genetics ; Mothers ; Mutation ; genetics ; Parents ; Polymorphism, Single Nucleotide ; Rett Syndrome ; genetics

OBJECTIVETo provide genetic diagnosis and counseling for a 2-year-old girl with typical Rett syndrome through analyzing the methyl-CpG binding protein 2 (MECP2) gene.

METHODSPotential mutation of the MECP2 gene was screened by DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis of members of the family as well as normal controls. Lymphocyte culture for karyotype analysis was carried out for the patient to exclude chromosomal abnormalities.

RESULTSThe karyotype of the girl was normal. No variation of the MECP2 gene was detected in the patient by direct sequencing. A heterozygosis variation, c.1072G>A in exon 4 of the MECP2 gene was detected in a normal female control, which was not found in other controls. The son and daughter of the female control were respectively heterozygous and homozygous carriers of the same mutation. By MLPA analysis, a heterozygosis deletion of exon 3 and part of exon 4 was detected in the patient. cDNA amplification and sequencing confirmed the presence of a 1176 bp deletion (c.27-1202del1176). The same deletion was not detected in the parents.

CONCLUSIONA large deletion in MECP2 gene was detected with MLPA in a patient featuring typical Rett syndrome. The same deletion was missed by sequencing analysis. With cDNA sequencing, the breakage point of the mutation can be mapped precisely.

Base Sequence ; Child, Preschool ; Exons ; Female ; Genetic Testing ; Genotype ; Humans ; Karyotyping ; Methyl-CpG-Binding Protein 2 ; genetics ; Mutation ; Rett Syndrome ; genetics

OBJECTIVERett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females as sporadic cases due to de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Familial cases of RTT are rare and are due to X-chromosomal inheritance from a carrier mother. Recently, DNA mutations in the MECP2 have been detected in approximately 84.7% of patients with RTT in China. To explain the sex-limited expression of RTT, it has been suggested that de novo X-linked mutations occur exclusively in male germ cells resulting therefore only in affected daughters. To test this hypothesis, we have analyzed the parental origin of mutations and the XCI status in 15 sporadic cases with RTT due to MECP2 molecular defects.

METHODSAllele-specific PCR was performed to amplify a fragment including the position of the mutation. The allele-specific PCR products were sequenced to determine which haplotype contained the mutation. It was then possible to determine the parent of origin by genotyping the single nucleotide polymorphism (SNP) in the parents. The degree of XCI and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes by analyzing CAG repeat polymorphism in the androgen receptor gene (AR).

RESULTSExcept for 2 cases who had a frameshift mutation; all the remaining 13 cases had a C-->T transition mutation. Paternal origin has been determined in all cases with the C-->T transition mutation. For the two frameshift mutations, paternal origin has been determined in one case and maternal origin in the other. The frequency of male germ-line transmission in mutations is 93.3%. Except for 2 cases who were homozygotic at the AR locus, of the remaining 13 cases, 8 cases had a random XCI pattern; the other five cases had a skewed XCI pattern and they favor expression of the maternal origin allele.

CONCLUSIONDe novo mutations in sporadic RTT occur almost exclusively on the paternally derived X chromosome and that this is most probably the cause for the high female: male ratio observed in sporadic cases with RTT. Random XCI was the main XCI pattern in sporadic RTT patients. The priority inactive X chromosome was mainly of paternal origin.

Chromosome Aberrations ; Chromosomes, Human, X ; Female ; Humans ; Male ; Methyl-CpG-Binding Protein 2 ; genetics ; Mutation ; Polymorphism, Single Nucleotide ; Rett Syndrome ; genetics ; X Chromosome Inactivation