 found most frequently in this population — 887-10A to G and 1048C to T. (Of note, A refers to adenine, T to thymine, C is cytosine, and G stands for guanine, the four building blocks of DNA).
“The [887-10A to G] mutation was first described in CLN2 disease in Portugal, and the authors proposed that the mutant protein might retain some residual activity, leading to a late-onset and delayed progressive form of CLN2,” the researchers wrote.
Three previously unknown mutations also were detected — 1226G to A, 1343C to A, and 1552-1G to A. The “impact of these mutations on TPP1 structure, activity and [symptoms] remains to be determined,” the researchers wrote.
“Data from this cohort of Latin American patients with atypical CLN2 show that potential differences between atypical and classical phenotypes include a later onset of disease, and that motor manifestations may not be so common as the first symptoms,” the researchers wrote.
“In light of the availability of specific therapy that may alter disease progression, these findings strengthen the importance of clinical suspicion and investigation of CLN2 even in patients above the classical age of the disease onset who present mainly with seizures but also language or behaviour abnormalities,” they added.