The neurofilament light chain polypeptide (NEFL) forms the major intermediate filament in neurons and axons. NEFL mutation is a cause of axonal or demyelinating forms of dominant Charcot-Marie-Tooth disease (CMT). We investigated NEFL in 223 Japanese CMT patients who were negative for PMP22, MPZ, GJB1, LITAF, EGR2, GDAP1, MTMR2 and PRX in the demyelinating form and negative for MFN2, MPZ, GJB1, HSP27, HSP22 and GARS in the axonal form. We detected four heterozygous missense mutations-Pro8Leu, Glu90Lys, Asn98Ser and Glu396Lys--in five unrelated patients and a homozygous nonsense mutation, Glu140Stop, in one other patient. All patients had mildly to moderately delayed nerve conduction velocities, possibly caused by a loss of large diameter fibers. This is the first report of a homozygous nonsense mutation of NEFL. Results of our study show that nonsense NEFL mutations probably cause a recessive phenotype, in contrast to missense mutations, which cause a dominant phenotype.

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Sera obtained from patients with non‐A, non‐B hepatitis were examined for the presence of hepatitis C virus (HCV) genome by using the reverse transcription‐polymerase chain reaction assay, as well as for antibody to HCV (anti‐HCV) by using an enzyme‐linked immunosorbent assay (ELISA). We also examined the presence of HCV RNA in liver tissue obtained by surgical resection of hepatocellular carcinoma. Among 33 patients, HCV RNA was detectable in 21 (64%), and the antibody was also positive in 21 (64%). Eighteen (55%) patients were positive for both assays. The two assays gave inconsistent results in 3 patients who were positive for HCV RNA but negative for anti‐HCV, and in 3 other patients who were negative for HCV RNA and positive for anti‐HCV. HCV RNA was also detected in 6 out of 10 non‐cancerous liver tissue specimens and in 3 out of 7 tumor tissue specimens. Using the polymerase chain reaction, the HCV genome was detected directly in many specimens obtained from patients with non‐A, non‐B hepatitis, suggesting the presence of replicating virus in patients positive for anti‐HCV. In addition, the differing results of the two assay systems suggest that the application of both is important for evaluation of the status of HCV infection.

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