Key result
Andersen-Tawil syndrome with KCNJ2 mutation presents without cardiac involvement despite facial dysmorphisms and periodic paralysis.
Why the study?
Although cardiac involvement is usually present in most ATS1 cases with KCNJ2 mutations, genotype-phenotype correlations are unclear and some mutations may show variable cardiac manifestations.
Case Report (n=1)
This case highlights the incomplete penetrance and lack of genotype-phenotype correlation in KCNJ2 mutations associated with Andersen-Tawil syndrome, specifically regarding cardiac involvement.
ATS1 case without cardiac involvement extends phenotypic spectrum; leaves open modifier contributions to penetrance.
The Andersen-Tawil syndrome (ATS) is characterized by hypo-normokaliemic muscle periodic paralysis, dysmorphic features and ventricular arrhythmias. Most cases are caused by mutations in KCNJ2, encoding for the potassium inwardly rectifying channel, Kir2.1 (ATS1). Although KCNJ2 mutations show no obvious genotype-phenotype correlations and incomplete penetrance, signs of cardiac involvement are usually present in most ATS1 cases. In contrast, here we describe an Italian ATS1 patient, carrying a c.574A→G mutation in KCNJ2, who had both facial dysmorphisms and muscle periodic paralysis but who did not manifest any cardiac involvement, although the same mutation was originally described in a Japanese kindred, in which all affected individuals manifested a severe cardiac phenotype.
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Modoni et al. (2011) conducted a case report in Andersen-Tawil syndrome (n=1). c.574A→G mutation in KCNJ2 was evaluated on Cardiac involvement. An Italian patient with Andersen-Tawil syndrome carrying a c.574A→G mutation in KCNJ2 presented with facial dysmorphisms and muscle periodic paralysis but lacked any cardiac involvement.
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