Clinical and electrodiagnostic findings, nerve biopsy and blood group markers in a family with hereditary neuropathy with liability to pressure palsies

Fulminant case of hereditary neuropathy with liability to pressure palsy

Hereditary neuropathy with liability to pressure palsy (HNPP) is typified as isolated nerve palsies caused by trivial compression or trauma. It rarely presents in two extremities and even more infrequently affects all four limbs simultaneously. We present a patient who concurrently experienced right shoulder, left hand, and bilateral foot weakness mimicking several multifocal conditions. Electromyography suggested HNPP and subsequent nerve biopsy and genetic testing were confirmatory. The case demonstrates that HNPP can present in a fulminant manner and should be included in the differential diagnosis of acute multiple mononeuropathies. The possible causes for such a rapid clinical course in our patient are discussed.

DNA analysis as a tool to confirm the diagnosis of asymptomatic hereditary neuropathy with liability to pressure palsies (HNPP) with further evidence for the occurrence of de novo mutations

We performed DNA analysis in four families with hereditary neuropathy with liability to pressure palsy (HNPP). An interstitial deletion of the 17 p11.2 region was found in typically affected patients as well as in as yet asymptomatic patients. The opportunity for an individual genotyping permitted to ascertain a de novo deletion in one clinically affected case with no relevant familial history. DNA analysis thus becomes the most sensitive tool in diagnosing HNPP, since potentially affected patients may lack either informative familial history, or clinical symptoms or even suggestive EMG or histopathological data (tomaculas).

Gene for hereditary neuropathy with liability to pressure palsies (HNPP) maps to chromosome 17 at or close to the locus for HMSN type 1

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder with an increased susceptibility of peripheral nerves to mechanical lesions resulting in transient nerve palsies. Many carriers remain asymptomatic but can be traced by electrophysiological examination, thereby demonstrating that HNPP is a generalised polyneuropathy. By using highly polymorphic markers linkage analysis was performed in a large family with HNPP. This resulted in a maximum lod score of 4.20 at theta = 0.10 with D17S520. Three-point linkage suggests that the gene for HNPP is located on chromosome 17 in the region between D17S250 (q11.2-q12) and D17S520 (p12), a region that has recently been shown to encompass a locus for another hereditary neuropathy, hereditary motor and sensory neuropathy type 1 (HMSN type 1). This raises the possibility that HNPP and this form of HMSN type 1 are allelic. In keeping with this speculation is our recent finding that D17S122, another marker from the HMSN type 1 region, displays apparent loss of heterozygosity in this family.

Hereditary neuropathy with liability to pressure palsies: a clinical, electroneurophysiological and morphological study

Clinical, electroneurographic and myographic studies were performed on 99 patients of 13 families having hereditary neuropathy with liability to pressure palsies (HNPP) and on 116 relatives. Diagnosis was confirmed in all families by a nerve biopsy of the index case. Large focal myelin thickenings (tomacula) were found in nerve biopsies of affected persons, whether or not pressure palsies had occurred. By using three electroneurographical parameters it was possible to discriminate between asymptomatic patients and unaffected relatives. Complaints sometimes mentioned in literature as being associated with HNPP such as low back pain, brachialgia and short lasting paraesthesia are not related to HNPP. The hereditary transmission is autosomal dominant with total penetration but variable expression.