OBJECTIVETo explore the genetic cause for two familial Angelman syndrome cases and correlation between the clinical phenotypes and their genetic basis.

METHODSKaryotyping analysis and microarray assay were carried out to exclude chromosome anomalies and uniparental disomy. The UBE3A gene was analyzed for potential point mutations, deletions, insertions and splice site mutations. Reverse transcription PCR was used to evaluate splicing mutation of the RNA transcripts.

RESULTSDNA sequencing showed the proband of family 1 has carried a novel maternal UBE3A splice acceptor site mutation, resulting in a guanine-to-cytosine transversion (IVS15-1G>C). Reverse transcription PCR revealed the proband and his mother both carried heterozygous mutant transcripts with loss of 54 and 59 nucleotides in exon 16, respectively. The proband displayed severe mental retardation, ataxia, seizures and inappropriate laughter. The siblings of family 2 has carried a novel maternal missense mutation in exon 16 of the UBE3A gene (c.2540C>T). She also presented with mental retardation, absent speech, mild ataxia and inappropriate laughter.

CONCLUSIONThe novel IVS15-1G>C and c.2540 C>T mutations of the UBE3A gene probably underlie the AS in the two families. Compared with small-scale mutations, larger fragments mutations can produce more severe phenotypes.

Angelman Syndrome ; genetics ; Female ; Humans ; Karyotyping ; Male ; Mutation ; Ubiquitin-Protein Ligases ; genetics

OBJECTIVETo analyze a case with Angelman syndrome (AS) using single nucleotide polymorphism array (SNP array) and explore its genotype-phenotype correlation.

METHODSG-banded karyotyping and SNP array were performed on a child featuring congenital malformations, intellectual disability and developmental delay. Mendelian error checking based on the SNP information was used to delineate the parental origin of detected abnormality. Result of the SNP array was validated with fluorescence in situ hybridization (FISH).

RESULTSThe SNP array has detected a 6.053 Mb deletion at 15q11.2q13.1 (22,770,421- 28,823,722) which overlapped with the critical region of AS (type 1). The parents of the child showed no abnormal results for G-banded karyotyping, SNP array and FISH analysis, indicating a de novo origin of the deletion. Mendelian error checking based on the SNP information suggested that the 15q11.2q13.1 deletion was of maternal origin.

CONCLUSIONSNP array can accurately define the size, location and parental origin of chromosomal microdeletions, which may facilitate the diagnosis of AS due to 15q11q13 deletion and better understanding of its genotype-phenotype correlation.

Angelman Syndrome ; genetics ; Child ; Genotype ; Humans ; Karyotyping ; methods ; Male ; Phenotype ; Polymorphism, Single Nucleotide ; genetics

OBJECTIVETo investigate the clinical manifestations and EEG characteristics of Angelman syndrome in children, and to strengthen the recognition of this disease.

METHODFourteen children with Angelman syndrome received video EEG monitoring, head MRI/CT and gene test, 11 patients received the metabolic investigations (e.g., lactic acid, ammonia, GC/MS and MS/MS). Eight patients received Gesell test. The patients were followed up for 1-3 years.

RESULTOf the 14 cases, 4 were male and 10 female, their age was from 8 months to 3 years and 7 months. The clinical characteristics included prominent lower jaw and wide mouth, fair skin and yellow hair, light-colored iris, paroxysmal laughter, astasia and language backward. Twelve patients had epileptic seizures; 10 patients displayed non-convulsive status epilepticus (NCSE), 9 patients displayed myoclonic, atypical absence, and non-convulsive seizure simultaneously; myoclonic, generalized tonic-clonic seizure and complex partial seizure in 1 each; 4 patients had fever in early seizures. The EEG showed paroxysmal middle-high amplitude 2-3 Hz spike and spinous slow-wave in 8 patients. Four patients showed paroxysmal frequently middle-high amplitude 2-3 Hz slow waves mixed with sharps. The other 2 patients showed a normal EEG. All the patients were diagnosed with genetics testing. The results included maternal deletion of chromosome 15q11-13 in 12, paternal uniparental disomy in 1 and imprinting defects in 1.

CONCLUSIONThere are characteristic clinical manifestation and craniofacial features in Angelman syndrome patients. Some patients have specific EEG patterns. Abnormal region of chromosome 15q11-13 is the basis of diagnosis.

Angelman Syndrome ; diagnosis ; genetics ; physiopathology ; Child, Preschool ; Electroencephalography ; Female ; Humans ; Infant ; Male

OBJECTIVE: To explore the genetic etiology for a Chinese pedigree affected with Angelman syndrome (AS). METHODS: The proband with phenotypes suggestive of AS was subjected to copy number variation sequencing (CNV-seq), methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and high-throughput next generation sequencing (NGS). Variant of the UBE3A gene was verified among family members by Sanger sequencing and bioinformatic analysis. RESULTS: NGS revealed that the proband has carried a heterozygous variant of the UBE3A gene, namely c.1517G>A (p.R506H). The variant has co-segregated with the disease in the pedigree. Multiple amino acid sequence alignment showed that the site of mutant residue is conserved among nine homologous species. The variant was predicted to be deleterious by bioinformatic analysis. CONCLUSION A novel variant of the UBE3A gene has been identified in a Chinese pedigree affected with AS. Above finding has further expanded the spectrum of UBE3A gene variants and phenotypes of AS, which also facilitated molecular diagnosis and genetic counseling for the family.
Angelman Syndrome/genetics* ; China ; DNA Copy Number Variations ; Humans ; Mutation ; Pedigree ; Phenotype

Angelman syndrome (AS) is a severe neurobehavioural disorder caused by failure of expression of the maternal copy of the imprinted domain located on 15q11-q13. There are different mechanisms leading to AS: maternal microdeletion, uniparental disomy, defects in a putative imprinting centre, mutations of the E3 ubiquitin protein ligase (UBE3A) gene. However, some of suspected cases of AS are still scored negative to all the latter mutations. Recently, it has been shown that a proportion of negative cases bear large deletions overlapping one or more exons of the UBE3A gene. These deletions are difficult to detect by conventional gene-scanning methods due to the masking effect by the non-deleted allele. In this study, we have used for the first time multiplex ligation-dependent probe amplification (MLPA) and comparative multiplex dosage analysis (CMDA) to search for large deletions affecting the UBE3A gene. Using this approach, we identified a novel causative deletion involving exon 8 in an affected sibling. Based on our results, we propose the use of MLPA as a fast, accurate and inexpensive test to detect large deletions in the UBE3A gene in a small but significant percentage of AS patients.
Angelman Syndrome/*genetics ; Child ; Female ; Gene Deletion ; Gene Dosage ; Genetic Testing ; Humans ; Male ; Ubiquitin-Protein Ligases/*genetics

OBJECTIVEAngelman syndrome (AS) is a neurodevelopmental genetic disorder that maps to 15q11-13. The primary phenotypes are attributable to loss of expression of imprinted UBE3A gene within this region which can arise by means of a number of mechanisms. The purpose of this study was to make a genetic diagnosis and to analyze the clinical features in suspected patients with AS.

METHODA total of 17 cases were diagnosed clinically as AS including 7 males and 10 females. The age at the time of diagnosis ranged from 8 months to 5 years. Genetic diagnosis was made by methylation-specific PCR (MS-PCR), linkage analysis by short tandem repeat (STR) and chromosome karyotype analysis. According to the international diagnostic criteria of AS, the related characteristic clinical features of the AS patients with deletion of 15q11-13 were analyzed and summarized.

RESULTDeletion of 15q11-13 was confirmed by genetic diagnosis in 17 AS patients. No abnormal findings were observed when they were born. Developmental delay in movement, speech impairments and happy disposition were observed in 100% (17/17) AS patients. And the severe speech deficit was much easier and more obvious to observe than movement. About 80% (14/17) - 90% (15/17) AS patients presented frequent clinical characteristics, such as seizures and abnormal EEG. However, microcephaly could only be observed in 35% (6/17) AS patients. Regarding the associated findings of AS, 41% (7/17) - 77% (13/17) AS patients could be observed with flat occiput/occipital groove, prognathia, wide mouth, wide-spaced teeth, frequent drooling, excessive mouth behaviors, hypopigmented skin, light hair compared to parents, flexed arm position during ambulation and sleep disorder etc. These features occurred at a higher frequency in those patients of > 2 years old group than that of < 2 years old group.

CONCLUSIONThe testing strategies of MS-PCR and STR linkage analysis combined with chromosome karyotype analysis were appropriate to the molecular genetic diagnosis of AS. In our analysis of clinical features, there was a lower rate of small head circumference (HC) in 35% patients compared with 80% patients in Caucasian with microcephaly, which might be attributable to the phenotypic heterogeneity in different races. And the birth history, movement and speech development and main clinical features of the Chinese AS patients were consistent with those of other studies. Clinical analysis in patients of different age groups showed that findings associated with AS would be more easily observed with the age increasing. Genetic diagnosis should be performed in clinically suspected AS patients.

Angelman Syndrome ; diagnosis ; genetics ; Child, Preschool ; Chromosome Deletion ; Chromosomes, Human, Pair 15 ; genetics ; Female ; Humans ; Infant ; Male ; Phenotype

OBJECTIVETo study the genetic diagnosis of Angelman syndrome(AS), and provide information for clinic diagnosis and counseling to AS families.

METHODSMethylation specific-PCR (MS-PCR) was used for primary diagnosis of 16 clinically suspected AS cases, and linkage analysis by short tandem repeat (STR) was applied to detect the molecular genetic defect in the nuclear families.

RESULTSIn this study, 10 AS patients were identified by MS-PCR, and 9 of them with maternal deletion in chromosome 15q11-q13, 1 with imprinting defect in chromosome 15q11-q13 were confirmed by STR linkage analysis.

CONCLUSIONMost of the AS patients could be confirmed by MS-PCR. And STR linkage analysis can detect the molecular defect of AS. It is very important for disease diagnosis, genetic counseling and prenatal diagnosis to perform the related genetic diagnosis.

Angelman Syndrome ; diagnosis ; genetics ; Chromosome Deletion ; Chromosomes, Human, Pair 15 ; genetics ; Female ; Genetic Linkage ; Humans ; Male ; Microsatellite Repeats ; Pedigree

OBJECTIVETo investigate the genotype-phenotype correlation in patients with Angelman syndrome/Prader-Willi syndrome (AS/PWS) and assess the application value of high-resolution single nucleotide polymorphism microarrays (SNP array) for such diseases.

METHODSTwelve AS/PWS patients were diagnosed through SNP array, fluorescence in situ hybridization (FISH) and karyotype analysis. Clinical characteristics were analyzed.

RESULTSDeletions ranging from 4.8 Mb to 7.0 Mb on chromosome 15q11.2-13 were detected in 11 patients. Uniparental disomy (UPD) was detected in only 1 patient. Patients with deletions could be divided into 2 groups, including 7 cases with class I and 4 with class II. The two groups however had no significant phenotypic difference. The UPD patient had relatively better development and language ability. Deletions of 6 patients were confirmed by FISH to be of de novo in origin. The risk to their sibs was determined to be less than 1%.

CONCLUSIONThe phenotypic differences between AS/PWS patients with class I and class II deletion need to be further studied. SNP array is useful in detecting and distinguishing of patients with deletion or UPD. This method may be applied for studying the genotype-phenotype association and the mechanism underlying AS/PWS.

Angelman Syndrome ; diagnosis ; genetics ; Child, Preschool ; Chromosome Deletion ; Female ; Genotype ; Humans ; Infant ; Karyotyping ; Male ; Phenotype ; Polymorphism, Single Nucleotide ; Prader-Willi Syndrome ; diagnosis ; genetics

BACKGROUNDAngelman syndrome (AS) is a neurogenetic disorder caused by an expression defect of the maternally inherited copy of ubiquitin protein ligase E3A (UBE3A) gene from chromosome 15. Although the most common genetic defects include maternal deletions of chromosome 15q11-13, paternal uniparental disomy and imprinting defect, mutations in the UBE3A gene have been identified in approximately 10% of AS patients.

METHODSA Chinese girl of 28 months presented clinical manifestation of AS. Genetic diagnosis and molecular genetic defects were studied by methylation-specific PCR (MS-PCR) and linkage analysis by short tandem repeat (STR). We further performed sequence analysis of all the coding exons and flanking sequences of the UBE3A gene. The novel mutation screening was also performed in 100 unrelated healthy individuals to exclude the possibility of identifying a polymorphism variation.

RESULTSThe MS-PCR analysis of the patient showed biparental inheritance of chromosome 15 with a normal methylation pattern in the 15q11-q13 region. And STR analysis revealed that the patient also inherited biparental alleles for six microsatellites. A novel mutation, cDNA1199 C> A (p.P400H), in exon 9 of the maternal UBE3A gene, was identified in the patient. Meanwhile, the mutation was observed in the patient's mother who had a normal phenotype.

CONCLUSIONSIt is necessary to perform the UBE3A gene mutation analysis in non-deletion/non-UPD/non-ID patients with AS. The clinical picture of the patient is concordant with that observed in previously reported AS patients with UBE3A mutation.

Angelman Syndrome ; genetics ; Child, Preschool ; Chromosomes, Human, Pair 15 ; genetics ; Female ; Humans ; Microsatellite Repeats ; Mutation, Missense ; genetics ; Polymerase Chain Reaction ; Ubiquitin-Protein Ligases ; genetics

OBJECTIVETo evaluate the conventional cytogenetic methods in genetic diagnosis and prenatal diagnosis in the family with a proband of Angelman syndrome (AS).

METHODSHigh-resolution G-banding karyotyping and fluorescence in situ hybridization (FISH) on metaphase chromosomes were performed.

RESULTSTwo AS patients and 1 normal fetus in the family were successfully detected by FISH.

CONCLUSIONOur result demonstrated that patient with type I AS could be detected by combining the techniques of high-resolution G-banding and FISH with clinical observation, which would offer accurate genetic counseling information to the geneticists and provide the prenatal diagnosis for the AS family.

Adult ; Angelman Syndrome ; diagnosis ; genetics ; Child, Preschool ; Chromosomes, Human, Pair 15 ; genetics ; Female ; Humans ; In Situ Hybridization, Fluorescence ; Infant ; Karyotyping ; Male ; Pregnancy ; Prenatal Diagnosis