Korean HNPP families research

May 8, 2004

Research from Exp Mol Med. Feb 29, 2004 ;36(1):28-35.

Hereditary neuropathy with liability to pressure palsies (HNPP) patients

of Korean ancestry with chromosome 17p11.2-p12 deletion.

Kim SM, Chung KW, Choi BO, Yoon ES, Choi JY, Park KD, Sunwoo IN.

Department of Neurology, College of Medicine, Yonsei University, Seoul

120-752, Korea.

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

autosomal dominant inherited disorder characterized by recurrent

pressure palsies. Most HNPP patients have a 1.5 mb deletion in

chromosome 17p11.2-p12. The present study aimed at evaluating the

deletion of the 17p11.2-p12 region in Korean subjects with families

exhibiting HNPP phenotype, and to determine the clinical,

electrophysiological and morphological aspects specifically associated

with this deletion in HNPP patients.

By genotyping six microsatellite markers (D17S921, D17S955, D17S1358,

D17S839, D17S122 and D17S261), HNPP with the deletion was observed in

79% (19 of 24) of HNPP families. Nerve conduction studies were performed

in 35 HNPP patients from these 19 families. The observed HNPP deletion

frequency in Koreans is consistent with findings in other populations.

Disease onset occurred at a significantly earlier age in patients with

recurrent pressure palsies than in those with a single attack (P <

0.01). Nerve conduction studies demonstrated diffuse mild to moderate

slowing of nerve conduction velocities that were worse over the common

entrapment sites, regardless of the clinical manifestations.

A long duration of compound muscle action potentials without a

conduction block or a temporal dispersion is a characteristic of this

disease. A sural nerve biopsy with teasing was performed in four

patients, and tomacula of the myelin sheath was found in 56.4%.

Our findings appear to support the existence of a phenotype/genotype

correlation in HNPP patients of Korean ancestry with the deletion, and

suggest that HNPP patients with earlier symptom onset face an increased

chance of having recurrent attacks.

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