Vacuolating megalencephalic leukoencephalopathy: 24 year follow-up of two siblings

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal recessive disorder with a chronic progressive course. The gene, MLC1, has been localized on chromosome 22qtell and 26 different mutations have been described. We report two siblings of non-consanguineous parents who presented with characteristic features of MLC. They showed macrocephaly from the first months of life. After a short time, motor clumsiness, ataxia, seizures and psychomotor retardation were observed. During childhood, both patients had a coma that lasted several days following a minor head trauma. The eldest sister experienced a permanent deterioration of the clinical picture after the coma. Epilepsy and electroencephalographic alterations were chronic, tending to improve during adulthood. Cerebral biopsy showed normal or minor changes in the cortical grey matter, and in the white matter gliosis, increased extracellular spaces and decreased numbers of fibres with thin myelin sheets. We have followed the patients during 24 years, from the ages of 4 and 8 years to the their present ages of 28 and 32 years. Clinical and neuro-imaging follow-up showed a chronic course with more prominent progression of the white matter abnormalities than of the neurological features. A homozygous mutation of the MLC1 gene was found in both siblings. The eldest patient, 32 years-old, needs a wheel-chair but has a good contact with the family and surrounding people. The youngest, 28-years-old, shows mild ataxia, spasticity and motor clumsiness, but she is able to participate in activities of daily life.