
Age at symptom onset is the strongest determinant of severity in TK2 deficiency. The panel defines the disease, its prevalence, and the presenting features that distinguish infantile, childhood, and late-onset patients.

Age at symptom onset is the strongest determinant of severity in TK2 deficiency. The panel defines the disease, its prevalence, and the presenting features that distinguish infantile, childhood, and late-onset patients.

Untreated survival ranges from about one year to two decades by onset age. Disease biology explains why muscle fails first, and early attention to swallowing and nutrition shapes outcomes.