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Angelman syndrome

Angelman syndrome

(Science: syndrome) a dysmorphic mental retardation syndrome, that has generated considerable interest in human genetics as a prototypic example of genomic imprinting in man.

Usually a sporadic disorder, it is characterised by profound intellectual deficiency, a striking puppet-like ataxic gait and facial features, paroxysmal laughter and seizures. These features are responsible for its alternative designation as happy puppet syndrome.

An interstitial deletion at chromosome band 15q12 was identified and can be detected in a large proportion of cases and the defect is linked to the gaba receptor gene. Chromosome haplotyping will always reveal the deletion to be carried on the maternally-derived chromosome 15, alternatively, angelman syndrome can be caused by uniparental disomy for the paternal chromosome 15. In both cases, this suggests that angelman syndrome results from loss or disruption of a gene (or genes) on chromosome 15 that must be inherited through the maternal gamete in order to be properly expressed.

The opposite phenomenon is seen in the prader-willi syndrome, in which a deletion of a nearby region on chromosome 15q is found on the paternally-derived chromosome, or there can be uniparental disomy for the maternally derived chromosome. Thus, both disorders seem to represent examples of genes which are subject to imprinting.


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parental definitions of chromosomes in heterozygous animals

... gene, its expression depends on its parantel origin. For example, Angelman syndrom/Prader-Willi syndrome are caused by the same genetic mutation; but their particular syndroms are different ...

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by DRT23
Sat Mar 19, 2011 10:44 am
 
Forum: Genetics
Topic: parental definitions of chromosomes in heterozygous animals
Replies: 1
Views: 1071

Genomic Imprinting In Humans (and classical genetics)

After looking Angelman and Prader-Willi syndrome up by Wikipedia, I have a question. The paternal gene is silent, which made by imprinting effects. ...

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by littlemonkey
Sat Jul 18, 2009 12:41 pm
 
Forum: Genetics
Topic: Genomic Imprinting In Humans (and classical genetics)
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Views: 8833

Re: Natural selection is proven wrong

... * Adrenal Hypoplasia Congenita * Adrenoleukodystrophy * Aicardi Syndrome * Alagille Syndrome * Albinism/Hypopigmentation * Alexander Disease ... * Alpha-1 Antitrypsin Deficiency * Alzheimer's Disease * Amblyopia * Angelman Syndrome * Anencephaly * Aniridia * Anophthalmia * Ataxia Telangiectasia ...

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by gamila
Thu Apr 23, 2009 4:16 am
 
Forum: Evolution
Topic: Natural selection is proven wrong
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