The patient in whom Roa et al. (1993) demonstrated the ser72-to-leu (S72L) substitution was an 8-year-old male who had severe hypotonia and weakness at birth, delayed motor milestones with normal speech development, and gradual improvement in motor abilities. He walked with the aid of leg braces and a walker at 7 years of age. There was marked distal atrophy of the lower limbs, mild weakness of the intrinsic hand muscles, and absent deep tendon reflexes in all 4 limbs. Sensory examination showed distal decrease in sensation to pinprick and temperature in all limbs. Motor nerve conduction velocity and sural nerve biopsy were typical of Dejerine-Sottas syndrome (DSS; 145900). The mother of the patient, who died at 30 years of age from respiratory failure, had a history of similar neuromuscular problems. DNA was not available from that patient.
Ionasescu et al. (1996) found the same mutation in a patient with Dejerine-Sottas syndrome who also showed sensorineural hearing loss, nystagmus, and peripheral facial nerve weakness. The S72L mutation had occurred de novo. The authors stated that nystagmus and peripheral facial nerve weakness had not previously been reported in Dejerine-Sottas syndrome.
Marques et al. (1998) detected the S72L mutation in a 7-year-old girl with Dejerine-Sottas syndrome. The authors proposed that ser72 may be a hotspot for mutation.
