Vacuoliting megalencephalic leukoencephalopathy with subcortical cysts, mapped to chromosome 22qtel.

The leukodystrophies form a complex group of orphan genetic disorders that primarily affect myelin, the main constituent of the brain white matter. Among the leukodystrophies of undetermined etiology, a new clinical entity called "vacuoliting megalencephalic leukoencephalopathy" (VL) was recently recognized. VL is characterized by diffuse swelling of the white matter, large subcortical cysts, and megalencephaly with infantile onset. Family studies in several ethnic groups have suggested an autosomal recessive mode of inheritance. We mapped the VL gene to chromosome 22qtel, within a 3-cM linkage interval between markers D22S1161 and n66c4 (maximum LOD score 10.12 at recombination fraction.0, for marker n66c4; maximum multipoint LOD score 17 for this interval) by genome scan of 13 Turkish families. Linkage analysis under the genetic-heterogeneity hypothesis showed no genetic heterogeneity. No abnormalities were found in three tested candidate genes (fibulin-1 and glutathione S-transferases 1 and 2).