Bernardo Dalla Bernardina

A recurrent 15q13.3 microdeletion syndrome associated with mental retardation and seizures

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 ∼0.3% (6/2,082 tested), a prevalence comparable to that of Williams, Angelman and Prader-Willi syndromes.

Molecular mechanisms generating and stabilizing terminal 22q13 deletions in 44 subjects with Phelan/McDermid syndrome

In this study, we used deletions at 22q13, which represent a substantial source of human pathology (Phelan/McDermid syndrome), as a model for investigating the molecular mechanisms of terminal deletions that are currently poorly understood. We characterized at the molecular level the genomic rearrangement in 44 unrelated patients with 22q13 monosomy resulting from simple terminal deletions (72%), ring chromosomes (14%), and unbalanced translocations (7%). We also discovered interstitial deletions between 17–74 kb in 9% of the patients. Haploinsufficiency of the SHANK3 gene, confirmed in all rearrangements, is very likely the cause of the major neurological features associated with PMS. SHANK3 mutations can also result in language and/or social interaction disabilities. We determined the breakpoint junctions in 29 cases, providing a realistic snapshot of the variety of mechanisms driving non-recurrent deletion and repair at chromosome ends. De novo telomere synthesis and telomere capture are used to repair terminal deletions; non-homologous end-joining or microhomology-mediated break-induced replication is probably involved in ring 22 formation and translocations; non-homologous end-joining and fork stalling and template switching prevail in cases with interstitial 22q13.3. For the first time, we also demonstrated that distinct stabilizing events of the same terminal deletion can occur in different early embryonic cells, proving that terminal deletions can be repaired by multistep healing events and supporting the recent hypothesis that rare pathogenic germline rearrangements may have mitotic origin. Finally, the progressive clinical deterioration observed throughout the longitudinal medical history of three subjects over forty years supports the hypothesis of a role for SHANK3 haploinsufficiency in neurological deterioration, in addition to its involvement in the neurobehavioral phenotype of PMS.

Recommendations of the Italian League Against Epilepsy Working Group on Generic Products of Antiepileptic Drugs

Summary:  The availability of generic products of antiepileptic drugs (AEDs) has been increasing in recent years. In view of the importance of the issue, the Italian League against Epilepsy (LICE) set up an ad hoc working group whose task was to assess available evidence on the efficacy and safety of generic AEDs in the treatment of epilepsy and to produce recommendations on their use. A careful review of the literature revealed no adequately powered randomized controlled trials that assessed the risk/benefit ratio of generic substitution. Although there have been reports of loss or worsened seizure control, or appearance of adverse events, following the switch from brand products to generics, a critical assessment of the evidence generally does not allow us to establish a cause–effect relationship between the switch and a change in clinical status. Overall, the working group concluded that generic AEDs meeting current regulatory criteria for bioequivalence represent a valuable choice in the management of epilepsy by allowing a substantial reduction of treatment costs, particularly in patients initiating monotherapy or adjunctive treament and in those with persistent seizures. The working group considered that in patients who achieved seizure freedom a modest change in plasma drug levels, which may occasionally occur even after substitution of products that meet bioequivalence criteria, could in rare cases lead to seizure breakthrough. Therefore, generic substitution is not recommended in patients who achieved seizure remission. Switches between a particular generic and another generic should also be preferably avoided. Finally, sustained‐release AED formulations should not be used interchangeably with immediate‐release brand or generic products. Patients need to be informed about the stringent criteria that currently govern the approval of generic products and about the implications of the use of generic AEDs, and their opinion should be taken into consideration at the time of prescribing.

PRRT2 Mutations are the major cause of benign familial infantile seizures

Mutations in PRRT2 have been described in paroxysmal kinesigenic dyskinesia (PKD) and infantile convulsions with choreoathetosis (PKD with infantile seizures), and recently also in some families with benign familial infantile seizures (BFIS) alone. We analyzed PRRT2 in 49 families and three sporadic cases with BFIS only of Italian, German, Turkish, and Japanese origin and identified the previously described mutation c.649dupC in an unstable series of nine cytosines to occur in 39 of our families and one sporadic case (77% of index cases). Furthermore, three novel mutations were found in three other families, whereas 17% of our index cases did not show PRRT2 mutations, including a large family with late‐onset BFIS and febrile seizures. Our study further establishes PRRT2 as the major gene for BFIS alone. Hum Mutat 33:1439–1443, 2012.

Cognitive development in Dravet syndrome: a retrospective, multicenter study of 26 patients.

Purpose:  To clarify the role of epilepsy and genetic background in determining the cognitive outcome of patients with Dravet syndrome.

Status epilepticus in benign rolandic epilepsy manifesting as anterior operculum syndrome.

Summary: We report the fourth case of partial status epilepticus (SE) in benign epilepsy of childhood with rolandic spikes (BECRS). The child suffered long‐lasting attacks involving the mouth and pharynx, clinically manifest as speech arrest, sialorrhea, and drooling. Both clinical and electroencephalogram (EEG) data were compatible with the diagnosis of BECRS. Only during SE was the clinical picture similar to that observed in the operculum or Foix‐Chavany‐Marie syndrome. SE remission was obtained with the usual antiepileptic drug therapy (diazepam, clobazam, valproate). EEG records showed additional patterns of continuous spike‐waves during slow sleep and specific inhibition and blocking of interic‐tal centrotemporal spikes by mouth and/or tongue voluntary movements.

Benign Familial Infantile Convulsions: Mapping of a Novel Locus on Chromosome 2q24 and Evidence for Genetic Heterogeneity

In 1997, a locus for benign familial infantile convulsions (BFIC) was mapped to chromosome 19q. Further data suggested that this locus is not involved in all families with BFIC. In the present report, we studied eight Italian families and mapped a novel BFIC locus within a 0.7-cM interval of chromosome 2q24, between markers D2S399 and D2S2330. A maximum multipoint HLOD score of 6.29 was obtained under the hypothesis of genetic heterogeneity. Furthermore, the clustering of chromosome 2q24-linked families in southern Italy may indicate a recent founder effect. In our series, 40% of the families are linked to neither chromosome 19q or 2q loci, suggesting that at least three loci are involved in BFIC. This finding is consistent with other autosomal dominant idiopathic epilepsies in which different genes were found to be implicated.

Early‐onset Absence Epilepsy and Paroxysmal Dyskinesia

Summary:  Purpose: To report on the association of childhood absence epilepsy and paroxysmal dyskinesia (PD).

Attention-deficit/hyperactivity disorder, Tourette's syndrome, and restless legs syndrome: The iron hypothesis

Preliminary but increasing evidence suggests that attention-deficit/hyperactivity disorder (ADHD), Tourettes syndrome (TS), and restless legs syndrome (RLS) may be comorbid. In the present article, we hypothesize that ADHD, TS, and RLS may be part of a spectrum, and that iron deficiency contributes to the pathophysiology underlying this spectrum. Iron deficiency might lead to ADHD, RLS and TS symptoms via its impact on the metabolism of dopamine and other catecholamines, which have been involved into the pathophysiology of ADHD, TS, and RLS. We speculate that the catecholaminergic systems are differently impacted in each of the three disorders, contributing to a different specific phenotypic expression of iron deficiency. MRI studies assessing brain iron levels in ADHD, TS, and childhood RLS, as well as genetic studies on the specific molecular pathways involved in iron deficiency, are greatly needed to confirm the iron hypothesis underlying ADHD, TS, and RLS. This body of research may set the basis for controlled trials assessing the effectiveness and tolerability, as well as the most appropriate dose, duration and type (oral vs. intravenous) of iron supplementation. In conclusion, the iron hypothesis may help us progress in the understanding of pathophysiological links between ADHD, RLS, and TS, suggesting that iron supplementation might be effective for all these three impairing conditions.

The 2q23.1 microdeletion syndrome: clinical and behavioural phenotype

Six submicroscopic deletions comprising chromosome band 2q23.1 in patients with severe mental retardation (MR), short stature, microcephaly and epilepsy have been reported, suggesting that haploinsufficiency of one or more genes in the 2q23.1 region might be responsible for the common phenotypic features in these patients. In this study, we report the molecular and clinical characterisation of nine new 2q23.1 deletion patients and a clinical update on two previously reported patients. All patients were mentally retarded with pronounced speech delay and additional abnormalities including short stature, seizures, microcephaly and coarse facies. The majority of cases presented with stereotypic repetitive behaviour, a disturbed sleep pattern and a broad-based gait. These features led to the initial clinical impression of Angelman, Rett or Smith–Magenis syndromes in several patients. The overlapping 2q23.1 deletion region in all 15 patients comprises only one gene, namely, MBD5. Interestingly, MBD5 is a member of the methyl CpG-binding domain protein family, which also comprises MECP2, mutated in Retts syndrome. Another gene in the 2q23.1 region, EPC2, was deleted in 12 patients who had a broader phenotype than those with a deletion of MBD5 only. EPC2 is a member of the polycomb protein family, involved in heterochromatin formation and might be involved in causing MR. Patients with a 2q23.1 microdeletion present with a variable phenotype and the diagnosis should be considered in mentally retarded children with coarse facies, seizures, disturbed sleeping patterns and additional specific behavioural problems.