This clinical trial is focused on studying a condition known as Frontotemporal Dementia with Progranulin Mutations (FTD-GRN). This is a type of dementia that affects the frontal and temporal lobes of the brain, often leading to changes in personality, behavior, and language. The treatment being tested in this study is called AVB-101, which is a solution designed for injection or infusion. AVB-101 is a special type of therapy that uses a Recombinant AAV-9 vector to deliver the human progranulin protein directly into the brain. This is done through a procedure called intrathalamic infusion, which involves administering the treatment into a specific area of the brain known as the thalamus.

The purpose of this study is to evaluate the safety and initial effectiveness of AVB-101 in individuals with FTD-GRN. Participants in the study will receive a one-time administration of AVB-101, and their health will be monitored over a period of time to observe any changes or side effects. The study will take place over several years, with an initial follow-up period of 26 weeks and a total follow-up period of up to five years. During this time, researchers will keep track of any adverse events, changes in vital signs, and other health indicators to ensure the treatment is safe and to gather preliminary data on its potential benefits.

Throughout the study, participants will undergo various assessments, including MRI scans and laboratory tests, to monitor their condition and the effects of the treatment. The study aims to provide valuable information on the safety and potential benefits of AVB-101 for people with FTD-GRN, contributing to the development of new treatment options for this challenging condition.