Interstitial 6q microdeletion syndrome and epilepsy : a new patient and review of the literature

Interstitial deletions of the long arm of chromosome 6 represent a rare genomic disorder. Variable phenotypes has been reported in patients carrying this deletion, including facial dysmorphisms, intellectual disability/developmental delay, growth retardation and hypotonia, upper limb and cardiac malformations, and Prader-Willi (PWS)-like features. We describe a new patient with an interstitial 6q deletion of 11.58 Mb detected by CGH-Array, who showed facial dysmorphic features, small hands and feet, and severe dorsal scoliosis. Ataxic gait and frequent hand stereotypies were also noted. She started having seizures at 14 years, characterized by loss of consciousness, clonic jerks of the limbs, roaring breathing, fixed gaze, and generalized hypotonia. In the course of the disease she experienced cluster of seizures requiring intensive treatment. The electroencephalographic recording showed slowing of the background activity and bilateral paroxysmal activity over the posterior regions. Review of the literature done to pinpoint the epileptological features of the syndrome identified heterogeneous descriptions of the electro-clinical picture in patients with interstitial 6q deletions. Genotype-phenotype correlations of this syndrome have been lacking until recently, when patients can be characterized with microarray-based comparative genomic hybridization. Description of additional patients with interstitial 6q deletions will help to delineate candidate genes associated with particular phenotypes.