[A new form of hereditary ataxia: X-linked congenital cerebellar hypoplasia (a clinical and molecular genetic analysis)].

There was performed the examination of a family with innate cerebellar hypoplasia. The disease was manifested in 7 males from 3 generations. X-linked recessive type of transmission of mutant gene was established. Clinical syndrome was characterized by delay of motor development during the first year of child's living as well as by ataxia, dysarthria, external ophthalmoplegia and nonprogressive course too. The signs of pronounced hypoplasia of hemispheres and vermis were found by means of computer and magneto-resonance investigation. Molecular genetic study (linkage-analysis) revealed that the gene of the disease was localized in proximal part of long X-chromosome's shoulder, exactly in XpII 21-q24 interval (38 centimorgan genetic distance). That was the first example of successful genetic mapping of the disease from the group of hereditary cerebellar hypoplasias.