De novo microdeletion of 5q14.3 excluding MEF2C in a patient with infantile spasms, microcephaly, and agenesis of the corpus callosum.

The 5q14.3 microdeletion syndrome has recently been recognized as a clinical entity manifesting as severe intellectual disability, epilepsy, and brain malformations. Analysis of the shortest region of overlap among patients with this syndrome and subsequent identification of nucleotide alterations in the coding region of myocyte enhancer factor 2C gene (MEF2C) have suggested MEF2C as the gene responsible for the 5q14.3 microdeletion syndrome. We identified a de novo 3.4-Mb deletion of 5q14.3 in a patient with infantile spasms, microcephaly, and brain malformation. The deleted region in the present patient was positional toward the centromere, and MEF2C was not included in the deleted region. However the neurological and dysmorphic features of the present patient resembled those of patients with the 5q14.3 microdeletion syndrome. We consider that a positional effect is the likely explanation for this evidence. To study the precise mechanism of this positional effect, further information is required on patients showing atypical deletions neighboring MEF2C.