The paired-class homeobox-containing gene, Cart1, is expressed in forebrain 
mesenchyme, branchial arches, limb buds and cartilages during embryogenesis. 
Here, we show that Cart1-homozygous mutant mice are born alive with acrania and 
meroanencephaly but die soon after birth-a phenotype that strikingly resembles a 
corresponding human syndrome caused by a neural tube closure defect. 
Developmental studies suggest that Cart1 is required for forebrain mesenchyme 
survival and that its absence disrupts cranial neural tube morphogenesis by 
blocking the initiation of closure in the midbrain region that ultimately leads 
to the generation of lethal craniofacial defects. Prenatal treatment of Cart1 
homozygous mutants with folic acid suppresses the development of the 
acrania/meroanencephaly phenotype.