Clinodactyly and syndactyly – diagnostic clues
for Andersen-Tawil syndromeA 38-year-old man was diagnosed, at the age of 18, with SCN4A-negative hyperkalaemic periodic paralysis. The diagnosis remained unchanged until his 8-year-old daughter suffered an exercise-induced syncope. Her EKG showed a polymorphic ventricular tachycardia. Patient's hands and feet, previously overlooked, became “neurologically” relevant since they were characteristic of Andersen-Tawil syndrome (Figure). A pathogenic KCNJ2 mutation (Arg218Trp) was found.
(A) Fifth digit clinodactyly and (B) syndactyly of the toes 2 and 3, highly suggestive of Andersen-Tawil syndrome. The face (not shown) had only mild phenotypical characteristics.
Andersen-Tawil syndrome is an autosomal dominant disorder characterized by the triad of periodic paralysis, ventricular arrhythmias, and dysmorphic features1. Phenotypical heterogeneity, even within a family, often delays the diagnose which is necessary since cardiac assessment is warrant2.
References
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1 Tawil R, Ptacek LJ, Pavlakis SG, DeVivo DC, Penn AS, Ozdemir C et
al. Andersen's syndrome: potassium-sensitive periodic paralysis,
ventricular ectopy, and dysmorphic features. Ann Neurol. 1994;35(3):326-30.
http://dx.doi.org/10.1002/ana.410350313
» https://doi.org/10.1002/ana.410350313 - 2 Davies NP, Imbrici P, Fialho D, Herd C, Bilsland LG, Weber A, et al. Andersen-Tawil syndrome: new potassium channel mutations and possible phenotypic variation. Neurology. 2005;65:1083-9.
