Abstract

Background: Genome-wide screening of patients with mental retardation using array comparative genomic hybridisation (CGH) has identified several novel imbalances. With this genotype-first approach, the 2q22.3q23.3 deletion was recently described as a novel microdeletion syndrome. The authors report two unrelated patients with a de novo interstitial deletion mapping in this genomic region and presenting similar “pseudo-Angelman” phenotypes, including severe psychomotor retardation, speech impairment, epilepsy, microcephaly, ataxia, and behavioural disabilities.

Methods: The microdeletions were identified by array CGH using oligonucleotide and bacterial artificial chromosome (BAC) arrays, and further confirmed by fluorescence in situ hybridisation (FISH) and semi-quantitative polymerase chain reaction (PCR).

Results: The boundaries and sizes of the deletions in the two patients were different but an overlapping region of about 250 kb was defined, which mapped to 2q23.1 and included two genes: MBD5 and EPC2. The SIP1 gene associated with the Mowat–Wilson syndrome was not included in the deleted genomic region.

Discussion: Haploinsufficiency of one of the deleted genes (MBD5 or EPC2) could be responsible for the common clinical features observed in the 2q23.1 microdeletion syndrome, and this hypothesis needs further investigation.