HEREDITARY NEUROPATHY WITH LIABILITY TO PRESSURE PALSIES - THE SAME MOLECULAR DEFECT CAN RESULT IN DIVERSE CLINICAL PRESENTATION

Hereditary neuropathy with liability to pressure palsies (HNPP) is a p eripheral nerve disorder characterized by autosomal dominant inheritan ce, recurrent pressure palsies, reduced motor and sensory conduction v elocities and sausage-like swellings (tomacula) of myelin sheaths in n erve biopsy. Two young adult patients are reported as index cases of t wo families in which HNPP was diagnosed. The first patient presented w ith recurrent pressure palsies, whereas the second suffered from fasci culations and myokymias in his right hand, with difficulty in writing, and upper and lower limb paraesthesias of 3 years' duration. Electrod iagnostic studies revealed slowing of conduction primarily in common s ites of compression in both patients. Sural nerve biopsy revealed the characteristic tomaculous swellings in both patients. DNA analysis sho wed that both patients have a deletion in chromosome 17p 11.2 which is found in the majority of HNPP cases. In light of the common molecular defect, the different clinical symptomatology of the two patients is discussed.