Hereditary Neuropathy with Liability to Pressure Palsies: A Clinical and Genetic Study of A Taiwanese Family

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 elec-trophysiological and genetic tests should be done to investigate this disorder. (Chang Gung Med J 2005;28:56-63) Key words: hereditary neuropathy, HNPP, nerve conduction, tomaculous neuropathy