Saneto, Russell P.

Abstract Genome sequencing of the heterogeneous primary mitochondrial disorders (PMD) frequently reveals variants of uncertain significance that require functional tests for diagnosis, and does not identify variants in all patients. We analyzed mitochondrial enzyme assays, blue native polyacrylamide gel electrophoresis (BN-PAGE) with in-gel activity staining, complex I assembly blot, and select protein abundances in fibroblasts of a case series of 204 PMD patients divided into functional classes, in comparison to 51 controls and 53 differential diagnostic conditions. Overall, sensitivity and specificity for respiratory chain enzyme assays were 46% and 93% respectively, for BN-PAGE 40% and 98%, for complex I assembly assay 49% and 99%. The overall sensitivity of all tests was 76%, specificity 93%, with positive predictive value 96% and negative predictive value 67%. Categories with high sensitivity were isolated complex deficiencies, nuclear DNA-encoded mitochondrial protein synthesis defects, co-factor defects, and mitochondrial amino-acyl-tRNA synthetase conditions when aided by protein abundance. Mitochondrial DNA mutations and maintenance disorders showed poor sensitivities. Secondary dysfunctions were rare. A complete battery of functional tests showed strong diagnostic clinical utility in fibroblasts. One sentence summary A combination of four mitochondrial functional tests to identify or confirm suspected primary mitochondrial disease in fibroblasts had good sensitivity and excellent specificity, well beyond what was perceived using enzyme assays only.

SummaryObjectiveThe multicenter National Infantile Spasms Consortium prospective cohort was used to compare outcomes and phenotypic features of patients with infantile spasms with and without hypsarrhythmia.MethodsPatients aged 2 months to 2 years were enrolled prospectively with new‐onset infantile spasms. Treatment choice and categorization of hypsarrhythmia were determined clinically at each site. Response to therapy was defined as resolution of clinical spasms (and hypsarrhythmia if present) without relapse 3 months after initiation.ResultsEighty‐two percent of patients had hypsarrhythmia, but this was not associated with gender, mean age, preexisting developmental delay or epilepsy, etiology, or response to first‐line therapy. Infants with hypsarrhythmia were more likely to receive standard treatment (adrenocorticotropic hormone, prednisolone, or vigabatrin [odds ratio (OR) 2.6, 95% confidence interval (CI) 1.4–4.7] and preexisting epilepsy reduced the likelihood of standard treatment (OR3.2, 95%CI1.9–5.4). Hypsarrhythmia was not a determinant of response to treatment. A logistic regression model demonstrated that later age of onset (OR1.09 per month, 95%CI1.03–1.15) and absence of preexisting epilepsy (OR1.7, 95%CI1.06–2.81) had a small impact on the likelihood of responding to the first‐line treatment. However, receiving standard first‐line treatment increased the likelihood of responding dramatically: vigabatrin (OR5.2 ,95%CI2–13.7), prednisolone (OR8, 95%CI3.1–20.6), and adrenocorticotropic hormone (ACTH;OR10.2, 95%CI4.1–25.8) .SignificanceFirst‐line treatment with standard therapy was by far the most important variable in determining likelihood of response to treatment of infantile spasms with or without hypsarrhythmia.

Summary Purpose To review the efficacy and tolerability of stiripentol in the treatment of U . S . children with D ravet syndrome. Methods U . S . clinicians who had prescribed stiripentol for two or more children with D ravet syndrome between March 2005 and 2012 were contacted to request participation in this retrospective study. Data collected included overall seizure frequency, frequency of prolonged seizures, and use of rescue medications and emergency room ( ER )/hospital visits in the year preceding stiripentol initiation, and with stiripentol therapy. We separately assessed efficacy in the following treatment groups: g roup A , stiripentol without clobazam or valproate; g roup B , stiripentol with clobazam but without valproate; g roup C , stiripentol with valproate but without clobazam; and g roup D , stiripentol with clobazam and valproate. In addition, adverse effects were recorded. Key Findings Thirteen of 16 clinicians contacted for study participated and provided data on 82 children. Stiripentol was initiated a median of 6.0 years after seizure onset and 1.2 years after diagnosis of D ravet syndrome. Compared to baseline, overall seizure frequency was reduced in 2/6 in g roup A , 28/35 in g roup B , 8/14 in g roup C , and 30/48 in g roup D . All children with prolonged seizure frequency greater than quarterly during the baseline period experienced a reduction in this frequency on the various treatment arms with stiripentol. Similarly, 2/4 patients in g roup A , 25/25 in g roup B , 5/10 in g roup C , and 26/33 in g roup D experienced reduction in frequency of rescue medication use and 1/1 in g roup A , 12/12 in g roup B , 3/5 in g roup C , and 18/19 in group D had reduction in frequency of ER /hospital visits. Adverse effects were reported in 38, most commonly sedation and reduced appetite. Four patients (5%) discontinued stiripentol for adverse effects and two (2%) for lack of efficacy. Significance Stiripentol is an effective and well‐tolerated therapy that markedly reduced frequency of prolonged seizures in D ravet syndrome.