Megalencephalic leukoencephalopathy with subcortical cysts; a founder effect in Israeli patients and a higher than expected carrier rate among Libyan Jews

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a progressive inherited neurological disorder characterized by macrocephaly, deterioration in motor functions and cerebellar ataxia. In Israel the disease is found in an increased frequency among Libyan Jews. The disease is caused by mutations in the MLC1 gene, which encodes a putative CNS membrane transporter. We describe three novel mutations (p.G59E, p.P92S, and 134_136insC) in seven MLC families. One of these mutations, p.G59E, was found in the vast majority of MLC patients in Israel. Screening of 200 normal Libyan Jewish individuals for the p.G59E mutation, revealed a carrier rate of 1/40 compared with an expected carrier rate of 1/81. Several explanations could account for this difference the most likely one is an admixture of the Libyan Jewish population.