GRN-related frontotemporal lobar degeneration is caused by pathogenic variants in the GRN gene, with inheritance following an autosomal dominant pattern. No clear correlations have been identified between specific GRN pathogenic variants and age of onset, disease duration, or clinical phenotype; clinical variability is documented as high among individuals carrying the same GRN pathogenic variant. Penetrance is approximately 90% by age 75 years, though apparent reduced penetrance has been observed on occasion. Published data indicate that 60% of individuals with a well-characterized GRN pathogenic variant were affected by age 60 years, and more than 95% were affected by age 70 years. Simplex cases—where only one affected individual is identified in a family—have been reported to carry de novo variants or demonstrate reduced penetrance; in one large French series, 3.2% of simplex FTD cases carried a GRN pathogenic variant.

GRN-FTD presents diagnostic challenges due to substantial overlap with other neurodegenerative conditions. Presentations that raise consideration of GRN-FTD include behavioral variant frontotemporal dementia, characterized by early behavioral disinhibition, apathy, loss of empathy, perseverative or compulsive behaviors, hyperorality and dietary changes, and executive or generative cognitive deficits with relative sparing of memory and visuospatial function. Primary progressive aphasia, particularly the nonfluent agrammatic variant, is another recognized presentation.

Neuropsychological testing may demonstrate early impairment on frontal lobe tasks or specific language dysfunction prior to the onset of frank dementia. Assessment may include measures of executive function such as the Trail-Making Test, proverb interpretation, categorical naming, and abstract pattern recognition tasks.

Neuroimaging is used to evaluate for conditions that may mimic frontotemporal dementia, including white matter diseases, frontotemporal focal lesions, frontal lobe tumors, and cerebrovascular disease. The differential diagnosis includes FTD associated with pathogenic variants in other causative genes, Parkinson disease, Alzheimer disease, Pick disease, and other inherited FTD disorders. The logopenic variant of primary progressive aphasia has not been associated with GRN-FTD based on published data.

No disease-specific treatment has been identified for GRN-FTD. Psychosocial support forms a documented component of clinical management, with occupational therapy and environmental and physical interventions commonly employed. Certain behavioral manifestations—including apathy, impulsivity, and compulsiveness—have been documented to show response to selective serotonin reuptake inhibitors in some individuals with GRN-FTD. Roaming, delusions, and hallucinations have been reported to respond to antipsychotic medications in some cases. Antipsychotic agents used in clinical practice for management of aggressive behavior are typically reassessed at short intervals with the aim of discontinuation as soon as feasible.

Caregiver burden from the behavioral changes and loss of judgment associated with GRN-FTD is documented as considerable. No FDA-approved treatments or foundational therapies are recorded in the current certified data for this condition.

GRN-FTD is a progressive neurodegenerative condition. Published data indicate that age of onset ranges from 35 to 87 years with a mean of approximately 65 years. Penetrance reaches approximately 90% by age 75 years. Median age at death has been reported at approximately 65.5 years in individuals with a GRN pathogenic variant, compared with approximately 69.0 years in those without an identified GRN variant. Most individuals with movement disorder involvement progressively lose the ability to walk. Individuals are commonly followed in memory disorder clinics or multidisciplinary clinics involving neurologic and psychiatric services.

Numerous active clinical trials are registered for GRN-related frontotemporal lobar degeneration and related frontotemporal dementia conditions, with 54 active trial records documented on ClinicalTrials.gov. Documented investigations include a Phase 1/2 clinical trial of a progranulin-targeted therapeutic agent in individuals with frontotemporal dementia and GRN mutations, biomarker surveillance studies using neurofilament markers in neurodegenerative conditions, and studies of speech-language interventions in primary progressive aphasia including work in bilingual speaker populations. Additional registered studies examine caregiver connection technologies in dementia, early psychiatric referral effects on mental health outcomes, and clinical trial readiness infrastructure to support future intervention trials for GRN-FTD. Multiple studies are actively recruiting participants.