Find information on thousands of medical conditions and prescription drugs.

Angelman syndrome

Angelman syndrome (AS) is neurological disorder in which severe learning difficulties are associated with a characteristic facial appearance and behavior. more...

Home
Diseases
A
Aagenaes syndrome
Aarskog Ose Pande syndrome
Aarskog syndrome
Aase Smith syndrome
Aase syndrome
ABCD syndrome
Abdallat Davis Farrage...
Abdominal aortic aneurysm
Abdominal cystic...
Abdominal defects
Ablutophobia
Absence of Gluteal muscle
Acalvaria
Acanthocheilonemiasis
Acanthocytosis
Acarophobia
Acatalasemia
Accessory pancreas
Achalasia
Achard syndrome
Achard-Thiers syndrome
Acheiropodia
Achondrogenesis
Achondrogenesis type 1A
Achondrogenesis type 1B
Achondroplasia
Achondroplastic dwarfism
Achromatopsia
Acid maltase deficiency
Ackerman syndrome
Acne
Acne rosacea
Acoustic neuroma
Acquired ichthyosis
Acquired syphilis
Acrofacial dysostosis,...
Acromegaly
Acrophobia
Acrospiroma
Actinomycosis
Activated protein C...
Acute febrile...
Acute intermittent porphyria
Acute lymphoblastic leukemia
Acute lymphocytic leukemia
Acute mountain sickness
Acute myelocytic leukemia
Acute myelogenous leukemia
Acute necrotizing...
Acute promyelocytic leukemia
Acute renal failure
Acute respiratory...
Acute tubular necrosis
Adams Nance syndrome
Adams-Oliver syndrome
Addison's disease
Adducted thumb syndrome...
Adenoid cystic carcinoma
Adenoma
Adenomyosis
Adenosine deaminase...
Adenosine monophosphate...
Adie syndrome
Adrenal incidentaloma
Adrenal insufficiency
Adrenocortical carcinoma
Adrenogenital syndrome
Adrenoleukodystrophy
Aerophobia
Agoraphobia
Agrizoophobia
Agyrophobia
Aicardi syndrome
Aichmophobia
AIDS
AIDS Dementia Complex
Ainhum
Albinism
Albright's hereditary...
Albuminurophobia
Alcaptonuria
Alcohol fetopathy
Alcoholic hepatitis
Alcoholic liver cirrhosis
Alektorophobia
Alexander disease
Alien hand syndrome
Alkaptonuria
Alliumphobia
Alopecia
Alopecia areata
Alopecia totalis
Alopecia universalis
Alpers disease
Alpha 1-antitrypsin...
Alpha-mannosidosis
Alport syndrome
Alternating hemiplegia
Alzheimer's disease
Amaurosis
Amblyopia
Ambras syndrome
Amelogenesis imperfecta
Amenorrhea
American trypanosomiasis
Amoebiasis
Amyloidosis
Amyotrophic lateral...
Anaphylaxis
Androgen insensitivity...
Anemia
Anemia, Diamond-Blackfan
Anemia, Pernicious
Anemia, Sideroblastic
Anemophobia
Anencephaly
Aneurysm
Aneurysm
Aneurysm of sinus of...
Angelman syndrome
Anguillulosis
Aniridia
Anisakiasis
Ankylosing spondylitis
Ankylostomiasis
Annular pancreas
Anorchidism
Anorexia nervosa
Anosmia
Anotia
Anthophobia
Anthrax disease
Antiphospholipid syndrome
Antisocial personality...
Antithrombin deficiency,...
Anton's syndrome
Aortic aneurysm
Aortic coarctation
Aortic dissection
Aortic valve stenosis
Apert syndrome
Aphthous stomatitis
Apiphobia
Aplastic anemia
Appendicitis
Apraxia
Arachnoiditis
Argininosuccinate...
Argininosuccinic aciduria
Argyria
Arnold-Chiari malformation
Arrhythmogenic right...
Arteriovenous malformation
Arteritis
Arthritis
Arthritis, Juvenile
Arthrogryposis
Arthrogryposis multiplex...
Asbestosis
Ascariasis
Aseptic meningitis
Asherman's syndrome
Aspartylglycosaminuria
Aspergillosis
Asphyxia neonatorum
Asthenia
Asthenia
Asthenophobia
Asthma
Astrocytoma
Ataxia telangiectasia
Atelectasis
Atelosteogenesis, type II
Atherosclerosis
Athetosis
Atopic Dermatitis
Atrial septal defect
Atrioventricular septal...
Atrophy
Attention Deficit...
Autoimmune hepatitis
Autoimmune...
Automysophobia
Autonomic dysfunction
Familial Alzheimer disease
Senescence
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Medicines

History

Dr. Harry Angelman, a pediatrician working in Warrington, Cheshire, first reported three children with this condition in 1965. It was initially presumed to be rare. In 1987, it was first noted that around half of the children with Angelman syndrome have a small piece of chromosome 15 missing (chromosome 15q partial deletion). Since this time the condition has been reported more frequently and the incidence is now thought to be 1 in 15,000 children.

Pathophysiology

Angelman syndrome is caused by the loss of the the normal maternal contribution to a region of chromosome 15, most commonly by deletion of a segment of that chromosome. Other causes include uniparental disomy, translocation, or single gene mutation in that region. A healthy person receives two copies of chromosome 15, one from mother, the other from father. However, in the region of the chromosome that is critical for Angelman syndrome, the maternal and paternal contribution express certain genes very differently. This is due to sex-related epigenetic imprinting; the biochemical mechanism is DNA methylation. If the maternal contribution is lost, the result is Angelman syndrome. (When the paternal contribution is lost, by similar mechanisms, the result is Prader-Willi syndrome.)

Angelman syndrome can also be the result of mutation of a single gene. This gene (Ube3a, part of the ubiquitin pathway) is present on both the maternal and paternal chromosomes, but differs in the pattern of methylation (Imprinting). The paternal silencing of the Ube3a gene occurs in a brain region-specific manner; the maternal allele is active almost exclusively in the hippocampus and cerebellum. The most common genetic defect leading to Angelman syndrome is an ~4Mb (mega base) maternal deletion in chromosomal region 15q11-13 causing an absence of Ube3a expression in the maternally imprinted brain regions. Ube3a codes for an E6-AP ubiquitin ligase, which chooses its substrates very selectively and the four identified E6-AP substrates have shed little light on the possible molecular mechanisms underlying the human Angelman syndrome mental retardation state.

Initial studies of mice that do not express maternal Ube3a show severe impairments in hippocampal memory formation. Most notably, there is a deficit in a learning paradigm that involves hippocampus-dependent contextual fear conditioning. In addition, maintenance of long-term synaptic plasticity in hippocampal area CA1 in vitro is disrupted in Ube3a -/- mice. These results provide links amongst hippocampal synaptic plasticity in vitro, formation of hippocampus-dependent memory in vitro, and the molecular pathology of Angelman syndrome.

Read more at Wikipedia.org


[List your site here Free!]


Review: health risks not higher in IVF children
From OB/GYN News, 12/15/04 by Kate Johnson

PHILADELPHIA -- Children conceived through in vitro fertilization do not have higher rates of cancer, malformations, or psychological or developmental delays, according to preliminary findings of the largest literature review on the subject to date.

Still, singleton IVF babies are at increased risk for premature birth (OR 1.95), perinatal mortality (OR 2.18), and very low birth weight (OR 2.7), compared singletons conceived naturally, reported Kathy Hudson, Ph.D., who is the director of the Genetics and Public Policy Center at Johns Hopkins University in Washington, D.C., which conducted the study.

IVF twins are at no greater risk than naturally conceived twins for these adverse outcomes, she said at the annual meeting of the American Society for Reproductive Medicine.

In addition, the study found evidence "suggestive [of] but not sufficient" to indicate that assisted reproductive technologies (ART) may increase the risk of two rare genetic disorders, Beckwith-Wiedemann syndrome and a form of Angelman's syndrome.

"We think this is of some concern and that it needs extra follow-up," said James Mills, M.D., an investigator in the study and chief of the pediatric epidemiology section of the National Institute of Child Health and Human Development.

Beckwith-Wiedemann syndrome occurs in about 1 in 15,000 births in the general population, and the specific form of Angelman's syndrome that is of concern--an imprinting defect--occurs even more rarely, in about 1 in 300,000 births. Thus, even though these conditions appear to occur four to seven times more commonly among ART children, their incidence remains rare, even in this population, Dr. Mills said.

The researchers undertook a systematic review of 169 published studies examining neonatal outcomes; malformations; genetic anomalies; cancer; and psychosocial, developmental, and health outcomes in ART children aged 1 year or older.

"There have been small studies suggesting increases in cancers and malformations and psychosocial delays in these children, so what we have found should be very comforting and reassuring to parents," Dr. Hudson said.

The study was cosponsored by the American Academy of Pediatrics and the American Society for Reproductive Medicine.

ARTICLES BY KATE JOHNSON

Montreal Bureau

COPYRIGHT 2004 International Medical News Group
COPYRIGHT 2005 Gale Group

Return to Angelman syndrome
Home Contact Resources Exchange Links ebay