HNPP: a clinical and genetic study of a Taiwanese family.

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(Note: HNPP is the genetic opposite of CMT. CMT is a duplication of

the PMP22 gene in chromosome 17p11, whereas HNPP is a deletion. Some

of the symptoms can be the same - Gretchen)

Chang Gung Med J. 2005 Jan;28(1):56-63.

Hereditary neuropathy with liability to pressure palsies: a clinical

and genetic study of a Taiwanese family.

Tsai YT, Kuo HC, Chu CC, Lin KP, Huang CC.

Department of Neurology, Chang Gung Memorial Hospital, Taipei.

Hereditary neuropathy with liability to pressure palsies (HNPP), an

autosomal dominant disorder, is characterized by recurrent isolated

nerve palsies, which are precipitated by trivial compression or

trauma. In this report, we present the clinical features,

electrophysiological studies, nerve biopsy results, and molecular

analyses of a Taiwanese family.

Among the 7 members evaluated, one latent and three symptomatic patients were

found who showed a heterogeneous presentation from asymptomatic to

characteristically recurrent peripheral neuropathy.

Electrophysiological studies revealed a general decrease in nerve conduction

velocities in all four patients with focal conduction slowing, especially at the

compression sites. A sural nerve biopsy with a teased fiber preparation in the

index patient demonstrated a typical tomaculous appearance. Molecular genetic

studies exhibited a deletion of the PMP22 gene in chromosome 17p11.2-12 in all 4

patients.

In conclusion, the diagnosis of HNPP might be overlooked if based on clinical

presentation only. Family survey and electrophysiological and genetic tests

should be done to investigate this disorder.