Focal polymicrogyria are associated with submicroscopic chromosomal rearrangements detected by CGH microarray analysis.

Polymicrogyria is a relatively common cortical malformation characterized by multiple small gyri with abnormal cortical lamination. The pathophysiological bases are heterogeneous and include extrinsic factors and genetic causes. Recent data has emphasized the high prevalence of chromosomal rearrangements in bilateral and mainly perisylvian polymicrogyria in the context of multiple congenital abnormalities. We present here two cases of rare submicroscopic abnormalities ascertained by array-comparative genome hybridization screening of 18 patients with polymicrogyria. The first patient is an 11 year-old female with developmental delay, behavioural disturbance, postnatal microcephaly, focal seizures and temporo-occipital polymicrogyria. She presented a 7.2 Mb terminal deletion in the 6q27 region. The second patient is a 3 year-old boy with psychomotor retardation, spastic diplegia and right temporal polymicrogyria who presented a 3 Mb duplication in the 22q11.2 region. These two patients exhibited focal temporal or occipital polymicrogyria without additional brain malformations or multiple congenital abnormalities. This data suggest that patients with polymicrogyria, even focal and/or unilateral and isolated forms, should be screened for submicroscopic chromosomal rearrangements using array-CGH.