Key result
Whole exome sequencing identified a de novo pathogenic heterozygous variant in KCNQ2 as the cause of a fever-induced hyperkinetic movement disorder in an 8-year-old boy.
Case Report (n=1)
This case expands the phenotypic spectrum of KCNQ2 variants to include fever-induced hyperkinetic movement disorders in childhood.
May prompt KCNQ2 testing in fever-induced pediatric hyperkinesia; leaves open expanded phenotypes pending validation.
The differential diagnosis of fever-induced movement disorders in childhood is broad. Whole exome sequencing has yielded new insights into those cases with a suspected genetic basis. We report the case of an 8-year-old boy with a history of neonatal seizures who presented with near-continuous hyperkinetic movements of his limbs during a febrile illness. Initial diagnostic testing did not explain his abnormalities; however, given the suspicion for a channelopathy, whole exome sequencing was performed and it demonstrated a de novo pathogenic heterozygous variant in KCNQ2. There is an expanding phenotypic spectrum of heterozygous alterations in KCNQ2; however, this report provides the first description of a pathogenic KCNQ2 variant fever-induced hyperkinetic movement disorder in childhood. We also review the literature of cases previously published with the same pathogenic variant.
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Dhamija et al. (2017) conducted a case report in Fever-induced hyperkinetic movement disorder (n=1). Pathogenic heterozygous variant in KCNQ2 was evaluated on Identification of genetic etiology. Whole exome sequencing identified a de novo pathogenic heterozygous variant in KCNQ2 as the cause of a fever-induced hyperkinetic movement disorder in an 8-year-old boy.
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