Giant axonal neuropathy in two siblings: clinical histopathological findings

Giant axonal neuropathy is a rare, severe autosomal-recessive neurologic disease affecting both the peripheral and the central nervous system. In this article, we describe a detailed clinicopathological report of two affected sibs from a consanguineous Turkish family.

The index patient was a 6.5-year-old girl. Her intellectual development was normal. At the age of 3, her parents noticed progressive lack of balance and deterioration of motor skills. On examination, she had paresis and sensory loss more marked distally. Her mental status was normal. Her older brother had similar findings.

Electrophysiological studies of young patients showed decreased median and ulnar nerve conduction velocities, absent peroneal motor potential, absent sensory nerve potentials and an EMG suggesting a neurogenic pattern. MRI showed mild cerebral and cerebellar atrophy. The nerve biopsy showed moderate myelinated nerve fibres loss, several regenerative clusters and multiple giant axons. Focal demyelination, hypertrophic "onion pulp" changes and endoneural fibrosis were also seen. Immunohistochemically, neurofilament protein accumulation was detectable in giant axons.

This consanguineous family with two affected siblings and healthy parents complies with autosomal-recessive inheritance in GAN. In the majority of reported GAN cases, CNS involvement is described early in the course of the disease, but these patients did not present any sign of CNS involvement. GAN is a rare genetic disease of childhood involving the central and peripheral nervous systems. The diagnosis is easy with clinical, electrophysiological, and histopathological features, if it has been done. Early diagnosis is important, because of possible prenatal diagnosis.