We report a recurrent microdeletion syndrome causing mental retardation, epilepsy and variable facial and digital dysmorphisms. We describe nine affected individuals, including six probands: two with de novo deletions, two who inherited the deletion from an affected parent and two with unknown inheritance. The proximal breakpoint of the largest deletion is contiguous with breakpoint 3 (BP3) of the Prader-Willi and Angelman syndrome region, extending 3.95 Mb distally to BP5. A smaller 1.5-Mb deletion has a proximal breakpoint within the larger deletion (BP4) and shares the same distal BP5. This recurrent 1.5-Mb deletion contains six genes, including a candidate gene for epilepsy (CHRNA7) that is probably responsible for the observed seizure phenotype. The BP4-BP5 region undergoes frequent inversion, suggesting a possible link between this inversion polymorphism and recurrent deletion. The frequency of these microdeletions in mental retardation cases is approximately 0.3% (6/2,082 tested), a prevalence comparable to that of Williams, Angelman and Prader-Willi syndromes.

Summary:Purpose: Benign myoclonic epilepsy in infancy (BMEI) is a nosologically well-defined entity, characterized by myoclonic seizures (MS) in normal children younger than 3 years and by a good long term prognosis. In some cases the seizures are reflex. We studied 22 cases to better define the electroclinical semeiology and evolution of the disorder.Methods: Serial electroclinical and neuropsychological assessments, both during wakefulness and during sleep, were performed in 22 otherwise healthy children with spontaneous (17) or reflex (5) MS, recorded by video-EEG-polygraphy since clinical onset.Results: Seizure onset was between 3 months and 4 years 10 months (50% during first year, 86% before the third year); in reflex cases onset, was earlier than the 14th month. MS recurred during wakefulness and slow sleep in all cases and during REM sleep in reflex cases. MS and related EEG discharges were synchronous or asynchronous. Often ictal EEG discharges were limited to the rolandic and vertex regions (falsely focal paroxysms). Several seizures were subtle and could have escaped recognition. Unusually frequent sleep startles were recorded mostly in reflex cases. MS were well controlled by treatment. At follow-up, between ages 3 and 19 years, four patients had occasional seizures; two had cognitive impairment and three had learning difficulties. No other seizures or cognitive deficits were observed in reflex cases.Conclusions: Seizures associated with BMEI are rarely truly generalized and are often so subtle and related to falsely focal paroxysms that their frequency can be underestimated. The reflex form is a well-defined variant with an early onset, peculiar electroclinical features, and a good prognosis.

In the version of this paper published online August 27, there were several errors in the author affiliations. The correct affiliations list appears with the print version in this issue and has been corrected online. Additionally, a label in Figure 1B has been corrected to read ''Fam 3 II.3'' instead of ''Fam 3 II.1.'' Finally, the legend for Figure 1 has been corrected so that the panel descriptions refer to the correct panels. The authors regret the errors.

We report on a new duplication case of 7q11.23, reciprocal of the Williams-Beuren (WB) deletion. The patient, a 13-year-old girl, was ascertained within an array-CGH screening of patients with epilepsy and neuronal migration defects. Similarly to the first reported patient, she showed serious difficulties in expressive language in the absence of severe mental retardation and marked dysmorphic features. Magnetic resonance imaging (MRI) of the brain revealed an abnormal development of the cerebral cortex in the left temporal lobe, which showed a simplified gyral pattern, and increased cortical thickness. This finding, which might explain poor language development, suggests that the WB critical region might harbour a dosage-sensitive gene controlling the molecular machinery of neuronal migration, with regional specificity and lateralization. It will be important to confirm our findings in newly diagnosed patients with dup(7)(q11.23). We expect to detect many more patients with the same duplication using widespread clinical implementation of high-resolution genome analysis.

Submicroscopic copy-number variations make a considerable contribution to the genetic etiology of human disease. We have analyzed subjects with idiopathic mental retardation (MR) by using whole-genome oligonucleotide-based array comparative genomic hybridization (aCGH) and identified familial and de novo recurrent Xp11.22-p11.23 duplications in males and females with MR, speech delay, and a peculiar electroencephalographic (EEG) pattern in childhood. The size of the duplications ranges from 0.8-9.2 Mb. Most affected females show preferential activation of the duplicated X chromosome. Carriers of the smallest duplication show X-linked recessive inheritance. All other affected individuals present dominant expression and comparable clinical phenotypes irrespective of sex, duplication size, and X-inactivation pattern. The majority of the rearrangements are mediated by recombination between flanking complex segmental duplications. The identification of common clinical features, including the typical EEG pattern, predisposing genomic structure, and peculiar X-inactivation pattern, suggests that duplication of Xp11.22-p11.23 constitutes a previously undescribed syndrome.