The Zic-1 gene, which encodes a zinc finger protein, is expressed in the developing or matured central nervous system in a highly restricted manner. The Zic gene is expressed in granule cells that make synaptic contact with Purkinje cells. Clearly Zic-1 is a gene critical to cerebellar pattern formation. The expression of Zic genes is first detected at gastrulation and at neurulation, becomes restricted to the dorsal neural ectoderm and the dorsal paraxial mesoderm. Zic-2 and Zic-3 are highly similar genes, especially in their product's zinc finger motif and by comparison of their genomic organization in that they share common exon-intron boundaries and belong to the same gene family. By comparison in function, Zic-2 is essential for the formation of the brain and Zic-3 is important for right and left axis formation. The Zic-1 gene has been mapped to chromosome 9 in mouse. The 5' flanking region of the Zic-1 gene contains a region-specific enhancer determined to be essential in in vivo and in vitro deletion analysis. The temporal profile of mRNA expression differs for each of the Zic gene products. The Drosophila odd-paired gene is highly homologous to the Zic gene family.