Paroxysmal tonic upgaze and partial tetrasomy of chromosome 15: a novel genetic association.
Paroxysmal tonic upgaze of childhood is an eye movement abnormality characterized by periodic episodes of conjugate upward eye deviation. Although the spectrum of paroxysmal tonic upgaze has broadened considerably, a specific pathophysiology has not been elucidated. We report an infant with paroxysmal tonic upgaze who presented to his pediatrician with associated hypotonia and gross motor delay. High-resolution chromosome analysis demonstrated a supernumerary dicentric bisatellited marker chromosome. Analysis revealed partial tetrasomy of 15q. Given the significant amount of euchromatin demonstrated, it is likely that the chromosomal abnormalities are causative for the constellation of manifestations in this patient. To date, a specific genetic abnormality has not been associated with paroxysmal tonic upgaze. The finding of a genetic association with paroxysmal tonic upgaze might help characterize the substrate for ophthalmologic manifestations. Further study in this chromosomal region in patients with paroxysmal tonic upgaze is warranted.
Joseph
Kevin
K
Department of Neurology, Child Neurology Service, Walter Reed Army Medical Center, Washington, DC 20307, USA. krjoseph1@hotmail.com
Avallone
John
J
Difazio
Marc
M
D000782:Aneuploidy; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D002658:Developmental Disabilities / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D009123:Muscle Hypotonia / Q000235:genetics; D015835:Ocular Motility Disorders / Q000235:genetics*