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Paediatric

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Genetic Disorders

Question
15 out of 49
 

Differential expression of same gene depending on parent of origin is referred to as - (AIIMS Nov 2014)



A Genomic imprinting
B Mosaicism

C Anticipation
D Nonpenetrance

Ans. A

Genomic imprinting

The phenomenon referred to as genomic imprinting leads to pereferential expression of an allele depending on its parental origin – Harrisons

Genomic imprinting

o Human inherits two copies of each gene, i.e. two alleles, from homologous maternal and paternal chromosomes.

o There is no functional difference between the genes derived from mother or the father.

o But, with respect to some genes, there are functional differences between the paternal gene and maternal gene.

o These differences result from an epigenetic process, called genomic imprinting.

o In most cases, genomic imprinting selectively inactivates either the maternal or paternal allel.

1. Maternal genomic imprinting

• Selective inactivation of maternal allel

• Example is Angelman syndrome

2. Paternal genomic imprinting

• Selective inactivation ofpatemal allel.

• Example is Prader-willi syndrome.

Genetic Disorders Flashcard List

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