Clinical phenotype associated with TANGO2 gene mutation.

The clinical picture associated with a Transport and Golgi Organization 2 (TANGO2) gene bi-allelic mutation is represented by encephalopathy and rhabdomyolysis marked by cardiac rhythm disorders and neurological regression. The presentation of encephalopathy is diverse and can range from isolated language delay and cognitive impairment in a child to multiple disabilities and spastic quadriparesis. Hypothyroidism has also been frequently reported. This article presents the clinical phenotype of seven children with a TANGO2 bi-allelic mutation. The mutation was found by sequencing a panel of genes associated with rhabdomyolysis. While the clinical picture represents generalized cases, there is phenotypic variability in, for example, the degree of disability for each patient. A TANGO2 gene mutation, nevertheless, represents a serious illness with a limited life expectancy due to an unpredictable risk of cardiac rhythm disorder and death, particularly during rhabdomyolysis. Although the natural history of the disease presents an evolution of rhabdomyolysis triggered by infections or effort, an early diagnosis is difficult due in part to the fact that there is a lack of specific biochemical marker or identifying symptoms in the early presentation of the disease. Clinicians must therefore consider the TANGO2 gene when confronted with rhabdomyolysis in a patient suffering from an early developmental disorder. In the meantime, management of the disease remains purely symptomatic.