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PurposeThe Clinical Genome Resource (ClinGen) CDH1 Variant Curation Expert Panel (VCEP) developed specifications for CDH1 variant curation with a goal to resolve variants of uncertain significance (VUS) and with ClinVar conflicting interpretations for effective medical care. In addition, the CDH1 VCEP continues to update these specifications in keeping with evolving clinical practice and variant interpretation guidelines.MethodsCDH1 variant classification specifications were modified based on updated genetic testing clinical criteria, new recommendations from ClinGen, and expert knowledge from ongoing CDH1 variant curations. Trained biocurators curated 273 variants using updated CDH1 interpretation guidelines and incorporated published and unpublished data provided by diagnostic laboratories. All variants were reviewed by the ClinGen VCEP and classifications submitted to ClinVar.ResultsUpdated CDH1-specific variant interpretation guidelines include eleven major modifications since the initial specifications from 2018. Using the refined guidelines, 97% (36/37) of variants with ClinVar conflicting interpretations were resolved into benign, likely benign, likely pathogenic, or pathogenic, and 35% (15/43) of VUS were resolved into benign or likely benign. Overall, 88% (239/273) of curated variants had non-VUS classifications.ConclusionThe development and evolution of CDH1-specific criteria by the expert panel results in decreased uncertain and conflicting interpretations of variants in this clinically actionable gene.

On rare occasions, torsion dystonia can rapidly worsen and produce life-threatening symptoms. We present reports on two children who had generalized dystonia and who demonstrate the management difficulties of "dystonic storms."

We present two families with adult-onset focal dystonias with marked variability in disease expression, discuss the clinical findings in relation to the literature, and comment on the difficulties in determining the pattern of inheritance.

Among the side effects attributed to sodium valproate administration, the production of a parkinsonian syndrome is very uncommon, particularly in children. We report a 12-year-old girl with secondary epilepsy; 7 days after the initiation of valproate therapy she developed parkinsonism that disappeared completely when valproate was replaced by carbamazepine. We discuss the possible role of alterations in GABAergic neurotransmission in the extrapyramidal syndrome that developed.