| Type | MGI:General | Description | the prospective forebrain ectoderm is correctly induced and patterned at E7.5, but subsequently fails to develop, as indicated by maker analysis mutants can be classified into 3 groups (I-III), with class I mutants (about 30%) showing complete absence of the forebrain, class II and III mutants (60%) showing a reduced forebrain, and 10% exhibiting a normal forebrain |