Phenotype HNPP (Hereditary Neuropathy With Liability to Pressure Palsies) Induced by Medical Procedures.

The phenotype HNPP (hereditary neuropathy with liability to pressure palsies) is caused by heterozygous deletion of the PMP22 gene. HNPP is clinically characterized by asymmetric focal sensory loss and muscle weakness. Reports of HNPP have been rare. In this article, we report the case of an asymptomatic woman with the HNPP mutation. After undergoing total knee arthroplasty, she developed a footdrop with prolonged recovery. We concluded (a) that the HNPP mutation may carry a high risk for certain surgical procedures not expected to cause neurologic deficits in normal patients and (b) that humans with the HNPP mutation can be asymptomatic. Lack of symptoms can contribute to underrecognition of the disease.