TPP1 and Delayed speech and language development: The most common and early symptom of classic CLN2 is language delay (consensus; LE: 4), beginning at an early age, around 2 years old.15, 16Patients may also develop normal language skills and present language regression around 3 years old.16Epileptic seizures are the second most common symptom (consensus; LE:4), appearing from 3 up to 6 years old,15, 16and it is the main reason for parents to seek medical care (consensus; LE: 5).