Peter D Turnpenny, Meena Balasubramanian, J Helen Cross, Manju A Kurian, Sanjay M Sisodiya, Alison Male, Jessica Radley, Susan Elizabeth Holder, Neeti Ghali, Virginia Clowes, Lucinda Carr, Pankaj B Agrawal, Claudia A L Ruivenkamp, Tamara T Koopmann, Demetria Demetriou, Aikaterini Vezyroglou, Miranda Splitt, Santosh R Mordekar, Sahar Mansour, Imelda Hughes, Eleanor Hay, George K Tofaris, Andrea H Németh, Andrew E Fry, Muriel Holder-Espinasse, Catherine A Brownstein, Saskia Koene, Katy Barwick, Rhoda Akilapa
Journal: Neurology 2022;99(14):e1511-e1526
PMID: 36192182
BACKGROUND AND OBJECTIVES
is associated with a broad spectrum of predominantly neurologic disorders, which continues to expand beyond the initially defined phenotypes of alternating hemiplegia of childhood, rapid-onset dystonia parkinsonism, and cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss syndrome. This phenotypic variability makes it challenging to assess the pathogenicity of an variant found in an undiagnosed patient. We describe the phenotypic features of individuals carrying a pathogenic/likely pathogenic variant and perform a literature review of all variants published thus far in association with human neurologic disease. Our aim is to demonstrate the heterogeneous clinical spectrum of the gene and look for phenotypic overlap between patients that will streamline the diagnostic process.
METHODS
Undiagnosed individuals with variants were identified within the cohort of the Deciphering Developmental Disorders study with additional cases contributed by collaborators internationally. Detailed clinical data were collected with consent through a questionnaire completed by the referring clinicians. PubMed was searched for publications containing the term "ATP1A3" from 2004 to 2021.
RESULTS
Twenty-four individuals with a previously undiagnosed neurologic phenotype were found to carry 21 variants. Eight variants have been previously published. Patients experienced on average 2-3 different types of paroxysmal events. Permanent neurologic features were common including microcephaly (7; 29%), ataxia (13; 54%), dystonia (10; 42%), and hypotonia (7; 29%). All patients had cognitive impairment. Neuropsychiatric diagnoses were reported in 16 (66.6%) individuals. Phenotypes were extremely varied, and most individuals did not fit clinical criteria for previously published phenotypes. On review of the literature, 1,108 individuals have been reported carrying 168 different variants. The most common variants are associated with well-defined phenotypes, while more rare variants often result in very rare symptom correlations, such as are seen in our study. Combined Annotation-Dependent Depletion (CADD) scores of pathogenic and likely pathogenic variants were significantly higher and variants clustered within 6 regions of constraint.
DISCUSSION
Our study shows that looking for a combination of paroxysmal events, hyperkinesia, neuropsychiatric symptoms, and cognitive impairment and evaluating the CADD score and variant location can help identify an -related condition, rather than applying diagnostic criteria alone.
Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
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