The value of nerve conduction velocities in the detection of hereditary motor sensory neuropathy type I (HMSN I) in children at risk was determined in 36 children under 10 years of age at the University of Western Ontario, London, Ontario, Canada. Clinical signs and slowed motor nerve conduction velocities were found in 17 of the 36 children who had 1 parent with HMSN I. Four children had slowed conduction velocities at 1 year of age or less. Clinical signs were subtle and included pes planus, distal foot wasting, weakness of ankle eversion and dorsiflexion, and areflexia. In all but 1 of the 17 affected patients the motor nerve conduction velocities were less than 40 m/s. Sensory potentials were abnormal in 7 children with HMSN I at ages 6-7 years. 
COMMENT. These data show that HMSN I can be detected in early childhood. Even at 1 year of age or less the motor conduction velocity is significantly slowed. Abnormal physical findings are found in all children who have slow conduction velocities. The signs may be subtle and not accompanied by disability. Pes planus was the most common foot abnormality in this series. Nerve hypertrophy was uncommon.
Dr. Sghirlanzoni et al., Milan, Italy, report two siblings with HMSN III (Dejerine-Sottas disease) whose parents were both affected with autosomal dominant axonal HMSN II. This family and others cited show the existence of an HMSN III phenotype resulting from the homozygous expressions of HMSN I and II genes. 
A 4-year-old child with severe hypertrophic peripheral neuropathy had antibodies to myelin glycoprotein of peripheral nerve . This anti-Po glycoprotein activity may have a role in pathogenesis of the neuropathy.