Agenesis of the corpus callosum (ACC) is among the most frequent human brain 
malformations with an incidence of 0.5-70 in 10,000. It is a heterogeneous 
condition, for which several different genetic causes are known, for example, 
ACC as part of monogenic syndromes or complex chromosomal rearrangements. We 
systematically evaluated the data of 172 patients with documented corpus 
callosum abnormalities in the records, and 23 patients with chromosomal 
rearrangements known to be associated with corpus callosum changes. All 
available neuroimaging data, including CT and MRI, were re-evaluated following a 
standardized protocol. Whenever feasible chromosome and subtelomere analyses as 
well as molecular genetic testing were performed in patients with disorders of 
the corpus callosum in order to identify a genetic diagnosis. Our results showed 
that 41 patients with complete absence (agenesis of the corpus callosum-ACC) or 
partial absence (dysgenesis of the corpus callosum-DCC) were identified. Out of 
these 28 had ACC, 13 had DCC. In 11 of the 28 patients with ACC, the following 
diagnoses could be established: Mowat-Wilson syndrome (n = 2), Walker-Warburg 
syndrome (n = 1), oro-facial-digital syndrome type 1 (n = 1), and chromosomal 
rearrangements (n = 7), including a patient with an apparently balanced 
reciprocal translocation, which led to the disruption and a predicted loss of 
function in the FOXG1B gene. The cause of the ACC in 17 patients remained 
unclear. In 2 of the 13 patients with DCC, unbalanced chromosomal rearrangements 
could be detected (n = 2), while the cause of DCC in 11 patients remained 
unclear. In our series of cases a variety of genetic causes of disorders of the 
corpus callosum were identified with cytogenetic anomalies representing the most 
common underlying etiology.