Haploinsufficiency

When one working copy is not enough

Haploinsufficiency is a loss-of-function mechanism in which a single functional copy of a gene does not make enough product for normal function, so losing or inactivating one copy is enough to cause disease. It marks a dosage-sensitive gene. In CMT, HNPP results from the loss of one PMP22 copy, the reciprocal of the CMT1A duplication.

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