Cases reported "Angelman Syndrome"

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1/65. angelman syndrome with uniparental disomy due to paternal meiosis II nondisjunction.

    We report a case of angelman syndrome (AS) with paternal uniparental disomy (pUPD) of chromosome 15. This 6-year-old girl with overgrowth had frequent, but only provoked laughter, was mildly ataxic with limb hypertonia, and had no intelligible speech. She had deep-set eyes, protruding tongue, and prominent chin. The karyotype was normal. DNA analysis with microsatellites from chromosome 15 showed no inheritance of maternal alleles both within and outside the AS critical region. Proximal markers showed reduction to homozygosity of paternal alleles, intermediate markers showed nonreduction, and distal markers reduction, thus suggesting a meiosis II nondisjunction event in the father with two crossovers. This is, to our knowledge, the first reported case of AS due to meiosis II nondisjunction. We present detailed physical measurements in this patient, adding to the clinical description of the milder phenotype in AS due to pUPD.
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2/65. A previously unrecognised phenotype characterised by obesity, muscular hypotonia, and ability to speak in patients with angelman syndrome caused by an imprinting defect.

    The clinical features of angelman syndrome (AS) comprise severe mental retardation, postnatal microcephaly, macrostomia and prognathia, absence of speech, ataxia, and a happy disposition. We report on seven patients who lack most of these features, but presented with obesity, muscular hypotonia and mild mental retardation. Based on the latter findings, the patients were initially suspected of having prader-willi syndrome. dna methylation analysis of SNRPN and D15S63, however, revealed an AS pattern, ie the maternal band was faint or absent. Cytogenetic studies and microsatellite analysis demonstrated apparently normal chromosomes 15 of biparental inheritance. We conclude that these patients have an imprinting defect and a previously unrecognised form of AS. The mild phenotype may be explained by an incomplete imprinting defect or by cellular mosaicism.
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3/65. Visual evoked potential evidence of albino-like chiasmal misrouting in a patient with angelman syndrome with no ocular features of albinism.

    An 8-month-old boy with global developmental delay, including visual and hearing inattention, was examined in the ophthalmic clinic. Monocular flash visual evoked potentials demonstrated a crossed asymmetry in scalp distribution, a feature considered to be pathognomic of albinism. Remarkably a foveal reflex was noted in each eye and this patient did not have nystagmus, iris transillumination, nor conspicuously pale fundi. The optic discs appeared normal. He was noted to have very fair skin and hair, with a small head and flat occiput. Cytogenetic studies demonstrated a microdeletion of the maternal chromosome 15q11-q13, and he was diagnosed with angelman syndrome.
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4/65. An unexpected recurrence of angelman syndrome suggestive of maternal germ-line mosaicism of del(15)(q11q13) in a Finnish family.

    angelman syndrome is a neuro-developmental disorder caused by genetic abnormalities affecting the maternal gene expression in the chromosome region 15q11-q13. In a study group of 45 Finnish Angelman patients, a recurrence of a del(15)(q11q13) was detected in one family. The mother's chromosomes 15 were structurally normal, whereas the patients and their unaffected brother shared an identical maternally derived haplotype outside the deletion region. These findings are suggestive of maternal germ-line mosaicism of del(15)(q11q13).
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5/65. fluorescence in situ hybridization detectable mosaicism for angelman syndrome with biparental methylation.

    We present a child with mild to moderate global developmental delay including severe speech impairment, inappropriate happy demeanor, wide-based gait, frequent ear infections with mild hearing loss, deep-set eyes, a wide mouth, widely-spaced teeth, normal head circumference, and no seizures. Results of peripheral blood lymphocyte chromosomal analysis with GTG banding were normal. However, fluorescence in situ hybridization (FISH) studies showed mosaicism for a deletion of probes (D15S10 and SNRPN) from the angelman syndrome (AS) critical region with approximately 40% of peripheral lymphocytes having the deletion. The deleted chromosome 15 also showed centromeric duplication, which was detected with a D15Z1 probe [46,XX, dic(15)(pter-->q11.1::p11.2-->q11. 1::q13-->qter)]. The same duplication pattern was observed in 30% of the nuclei obtained from a buccal smear. Methylation studies using polymerase chain reaction with sodium bisulfite-treated DNA demonstrated a normal biparental methylation pattern. To the best of our knowledge, this is the first case with AS and a FISH detectable deletion in a mosaic pattern. We recommend FISH studies for the detection of mosaicism in the patients with AS clinical findings even if results of the methylation studies are normal.
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6/65. FISH characterisation of dynamic mosaicism involving an inv dup(15) in a patient with mental retardation.

    We report on a man with mental retardation and a complex karyotype with cells containing up to three morphologically distinct supernumerary marker chromosomes (SMCs) in most metaphases. fluorescence in situ hybridisation studies using chromosome 15-specific probes characterised the presence of seven SMCs all derived from chromosome 15. The results suggest that the patient originally had a large inv dup(15) containing two copies of the Prader-Willi/Angelman critical region which became mitotically unstable, and by a process of dynamic mosaicism various morphologically distinct SMCs arose.
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7/65. drowning as a cause of death in angelman syndrome.

    angelman syndrome is characterized by mental retardation, seizures, ataxia, inappropriate laughter, lack of speech, a particular facial appearance, and generally a chromosome 15q11-q13 deletion. Recently, a fascination with water and water-related activities has been reported in individuals with the syndrome. We report on a 9.6-year-old male previously diagnosed with angelman syndrome who died unexpectedly by drowning in a shallow backyard wading pool. This case further illustrates the fascination with water by individuals with angelman syndrome and highlights that this fascination may lead to death. We wish to alert careproviders that this fascination with water and water-related activities may contribute to death and that these individuals should be closely supervised when in the presence of water.
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8/65. Split-cord malformation in a girl with angelman syndrome: a mere coincidence?

    We present a case of a girl with both angelman syndrome and split-cord malformation. The child was initially referred at the age of 2.5 years, for developmental delay and a possible diagnosis of spina bifida occulta, based on the presence of a hair tuft located on the midline of the lumbar area. magnetic resonance imaging of the spine showed split-cord malformation below L1, whereas a cytogenetically detected deletion of chromosome bands 15q11-q13 (SNRPN) confirmed the clinical diagnosis of angelman syndrome. Split-cord malformation or diastematomyelia is a rare form of spina bifida occulta that occurs sporadically and is not particularly related to specific syndromes. hair patches or other distinctive cutaneous stigmata such as those seen in the present case have not, to our knowledge, been reported in other patients with angelman syndrome; therefore, the association of angelman syndrome and split-cord malformation in this child is probably coincidental. spinal cord abnormalities have not been consistently reported in patients with angelman syndrome; only one adult patient with angelman syndrome and spina bifida occulta has been reported, and this association was probably considered fortuitous. However, some relatively uncommon clinical features such as deterioration of gait, lower limb malformations, and bladder dysfunction, particularly as the patients age, although nonspecific, are reminiscent of such a cause. We therefore urge clinicians to look for cutaneous stigmata along the spine and consider the evaluation of the spinal cord in children with apparent paraparesis, out of proportion to that usually seen in angelman syndrome, should our case report not just be a coincidental observation.
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9/65. Mild generalized epilepsy and developmental disorder associated with large inv dup(15).

    PURPOSE: Several studies attempted to clarify the genotype-phenotype correlations in patients with inverted duplication of chromosome 15 [inv dup(15)], which is usually characterized by severe mental retardation and epilepsy in individuals with large duplications including the Prader-Willi/Angelman region. We report two patients with inv dup(15) who, in spite of a large duplication, had a mild phenotype including adult-onset epilepsy. This report may help to define the milder spectrum of the syndrome. methods: A 25-year-old girl with mild mental retardation had a 6-year history of absence seizures, with occasional head drop. Interictal EEG revealed diffuse spike-wave complexes. epilepsy was well controlled by a combination of lamotrigine (LTG) and valproate (VPA). The other patient, a 27-year-old man with mild mental retardation, had a 5-year history of rare generalized tonic-clonic seizure during sleep, and frequent episodes of unresponsiveness, which appeared to be atypical absence seizures on video-EEG recordings. A combination of VPA and LTG led to a remarkable improvement, although no complete control. RESULTS: Molecular analysis revealed a large inv dup15 in both patients. CONCLUSIONS: The discrepancy between the mild phenotype and the severe chromosomal abnormality detected in these two patients further supports the notion that the site of breakpoint might be contributory to the inv dup(15) phenotype. Inv dup(15) should be considered in atypical cases of generalized epilepsy of adult onset without clear-cut etiology.
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10/65. Familial interstitial 570 kbp deletion of the UBE3A gene region causing Angelman syndrome but not prader-willi syndrome.

    angelman syndrome (AS) is a disorder of psychomotor development caused by loss of function of the imprinted UBE3A gene. Since the paternal UBE3A copy is regularly silent, only mutations inactivating the maternal copy cause AS. Among 1,272 patients suspected of AS, we found one with an isolated deletion of the UBE3A gene on the maternally inherited chromosome. Initial dna methylation testing at the SNURF-SNRPN locus in the patient revealed a normal pattern. The deletion was only detected through allelic loss at microsatellite loci D15S1506, D15S122, and D15S210, and confirmed with fluorescence in situ hybridization (FISH) using bacterial artificial chromosome (BAC) probes derived from the loci. It extends approximately 570 kilobase pairs (kbp), encompassing the UBE3A locus, and is flanked by loci PAR/SN and D15S986. The deletion is familial, and haplotype studies suggest that a great grandfather of the index patient already carried this deletion, and that it causes AS when inherited through the female germline but not prader-willi syndrome (PWS) when paternally inherited. Our findings support the hypothesis that the functional loss of maternal UBE3A gene activity is sufficient to cause AS and that the deleted region does not contain genes or other structures that are involved in PWS. Finally, this case highlights that methylation tests can fail to detect some familial AS cases with a recurrence risk of 50%.
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