• vacuolating megalencephalic leucoencephalopathy
• subcortical cysts
• common ancestral haplotype

• VL, vacuolating megalencephalic leucoencephalopathy with subcortical cysts

Vacuolating megalencephalic leucoencephalopathy with subcortical cysts (VL) is a newly described, inherited leucodystrophy (MIM 604004). Clinically, the disease is characterised by accelerated head growth beginning in the first year of life and resulting in extreme macrocephaly and mild delays in gross motor milestones. In most cases, these early manifestations are followed by evolution of pyramidal symptoms and signs, cerebellar ataxia, epilepsy, and in older patients dystonia and athetosis.¹ Cognitive function is relatively spared in most patients. Brain imaging with computed tomography (CT) or magnetic resonance imaging (MRI) shows diffuse cerebral white matter swelling with progressive cystic-like changes, prominent in the frontotemporal regions, with preservation of grey matter structures.^1,2 Pathological specimens from VL patients showed splitting of the myelin sheaths between the lamellae consistent with an oedematous process, with sparing of the exons.³ Although progressive in nature, VL is characterised by a relatively mild clinical course compared to the severity of the neuroradiological findings.^4,5 About 70 cases of the disease have been described in different ethnic groups. The molecular basis of this disorder remains unknown. The inheritance is autosomal recessive and the disease gene was recently mapped to a 3 cM interval between D22S1161 and the telomere of chromosome 22q.⁶ Linkage was established in a group of 13 Turkish families all originating from rural areas of central and south eastern Anatolia. No shared alleles or shared haplotypes were detected between the Turkish families.