Hypothalamic-pituitary dysfunction in alternating hemiplegia of childhood

Methodology of a Natural History Study of a Rare Neurodevelopmental Disorder: Alternating Hemiplegia of Childhood as a Prototype Disease

Here, we describe the process of development of the methodology for an international multicenter natural history study of alternating hemiplegia of childhood as a prototype disease for rare neurodevelopmental disorders. We describe a systematic multistep approach in which we first identified the relevant questions about alternating hemiplegia of childhood natural history and expected challenges. Then, based on our experience with alternating hemiplegia of childhood and on pragmatic literature searches, we identified solutions to determine appropriate methods to address these questions. Specifically, these solutions included development and standardization of alternating hemiplegia of childhood-specific spell video-library, spell calendars, adoption of tailored methodologies for prospective measurement of nonparoxysmal and paroxysmal manifestations, unified data collection protocols, centralized data platform, adoption of specialized analysis methods including, among others, Cohen kappa, interclass correlation coefficient, linear mixed effects models, principal component, propensity score, and ambidirectional analyses. Similar approaches can, potentially, benefit in the study of other rare pediatric neurodevelopmental disorders.

The diagnostic spectrum of ATP1A3-related disorders: 3 new patients

BACKGROUND

ATP1A3-related disorders are rare but increasingly recognized syndromes with overlapping phenotypes.

CLINICAL OBSERVATIONS

A male child and his mother with c.2452G>A (p.Glu818Lys) mutation and an unrelated child with c.2428A>T (p.Ile810Phe) mutation in the ATP1A3 gene are reported.

RESULTS

The first child presented with fever-induced flaccid unresponsiveness and the diagnosis was made after extensive negative workup except for abnormal EMG showing low amplitude motor responses with acute denervation; his symptomatic mother went undiagnosed for thirty years until his diagnosis. An unrelated male child presented with symptoms most consistent with the rapid-onset dystonia-Parkinsonism (RDP) phenotype but with intermediate features of alternating dystonia with choreoathetoid movements two years after a c.2428A>T (p.Ile810Phe) mutation was found.

CONCLUSION

ATP1A3-related disorders have variable manifestations and can remain undiagnosed for decades. Treatment remains mostly supportive. With the increasing use of genetic testing for broad indications, further research into effective therapies is necessary.