Which phenomenon explains why DM1 can become more severe in successive generations?

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Multiple Choice

Which phenomenon explains why DM1 can become more severe in successive generations?

Explanation:
Anticipation explains this: DM1 is caused by a CTG trinucleotide repeat expansion in the DMPK gene. The number of repeats often increases when passed to offspring, so each generation can inherit a longer expansion. The longer the repeat, the earlier the onset and the more severe the disease tends to be. This is why DM1 can appear more severe in successive generations, with congenital DM1 representing a severe outcome often seen when a larger expansion is transmitted from the mother. Other concepts like penetrance variability, genomic imprinting, or somatic mosaicism don’t account for worsening across generations.

Anticipation explains this: DM1 is caused by a CTG trinucleotide repeat expansion in the DMPK gene. The number of repeats often increases when passed to offspring, so each generation can inherit a longer expansion. The longer the repeat, the earlier the onset and the more severe the disease tends to be. This is why DM1 can appear more severe in successive generations, with congenital DM1 representing a severe outcome often seen when a larger expansion is transmitted from the mother. Other concepts like penetrance variability, genomic imprinting, or somatic mosaicism don’t account for worsening across generations.

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