Maternal uniparental disomy

Maternal uniparental disomy

Chromosome abnormality in which both chromosomes in a pair are inherited from one's mother.
Mentioned in: Prader-Willi Syndrome
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In 65%-75% of cases, the cause is a deletion of the father's chromosome in the 15q11-q13 region, 20%-30% of patients will have maternal uniparental disomy of chromosome 15, and a defect in the region that controls the imprinting process is responsible in only 1%-3% of patients (6,7).
The second is maternal uniparental disomy 15 (mUPD; when both copies of chromosome 15 are maternally inherited) found in 25% [8].
Prader-Willi syndrome (PWS) is a genetic disorder resulting from a defect within the Prader-Willi critical region on chromosome 15 due to paternal deletion, maternal uniparental disomy, or imprinting defect.
Prader-Willi syndrome (PWS; OMIM 176270) is a well-known complex genetic condition caused by a deficiency of paternally expressed genes in the chromosomal region 15q11-q13, due to a de novo deletion in the paternally derived chromosome 15 in 70-75%, while the rest is due to maternal uniparental disomy (25%), unbalanced translocations, and genomic imprinting defects, all involving chromosome 15.
Prader-Willi syndrome is considered to be the leading cause of obesity associated with genetic syndromes and has a prevalence of approximately 1/25000.11 The partial deletion of the long arm of the paternal chromosome 15 is a common marker of this disease, (12) though it can also present as a maternal uniparental disomy. (13)
Of all RSS patients, 38.5% have hypomethylation of chromosome 11p15.5 [3], and 10% have maternal uniparental disomy for chromosome 7 [4].
These mechanisms include a paternally derived de novo deletion of this region (approximately 75%-80%), maternal uniparental disomy (UPD) of chromosome 15 (approximately 20%-25%), or paternal imprinting defects that silence paternal alleles (approximately 1%).
In the population of persons with PWS resulting from maternal uniparental disomy, reduced skin picking was seen but there was an increase in affective, psychotic, and autistic symptoms (Boer et al., 2002; Soni et al., 2007).
But 28% of these cases are caused by maternal uniparental disomy which means that both chromosome 15's have been derived from the mother, a defect that can only be ascertained with molecular testing.
The causes of this disruption include paternal deletion (DEL) of 15q11-13 and maternal uniparental disomy 15 (mUPD, when both copies of chromosome 15 are maternally inherited) [1].

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