Submicroscopic deletions of 17p13.3 in type 1 Lissencephaly.

DNA markers YNZ22.1 and YNH37.3 were studied by Southern blotting in 14 patients with typical (11 cases) and atypical (3 cases) type 1 Lissencephaly, all with normal high resolution karyotype. A submicroscopic deletion was found in 2 typical cases: one with Miller-Dieker Syndrome (MDS), the other with Isolated Lissencephaly Sequence (ILS). These results suggest a genetic continuum between MDS and ILS. The low frequency of such deletions, especially in ILS, will necessitate direct testing of the newly identified LIS 1 gene.