Deletion 18p11.32p11.31 in a Child with Global Developmental Delay and Atypical, Drug-Resistant Absence Seizures.

We report the first case of an 18p11.32 deletion, detected by array CGH, associated with a drug-resistant form of atypical absence epilepsy, global developmental delay and no signs of holoprosencephaly (HPE). In particular, this region encompasses 19 genes, and none of these genes have been strictly associated with epilepsy. Among these, TGIF1 is expressed in the fetal and adult nervous system, and its deletion has been related to central nervous system diseases. TGIF1 deletions have previously been reported in patients with a comparable phenotype as seen in our case and in children whose neurological signs and symptoms were considerable, but not epileptiform. Mutations and deletions involving the TGIF1 gene have been described in patients with HPE in an autosomal dominant model of inheritance. However, TGIF1 mutations have also been reported in normal individuals and in patients with mental retardation or showing a very mild phenotype, suggesting the characteristic of incomplete penetrance and variable expressivity. Therefore, a TGIF1 deletion may not be always related to HPE, and it may have a link to the development of epilepsy.