FTLD-ALS (also known as FTLD-MND) is a rare neurodegenerative condition that represents the clinical overlap between Frontotemporal Lobar Degeneration (FTLD) and Amyotrophic Lateral Sclerosis (ALS). This syndrome demonstrates the biological intersection of TDP-43 proteinopathies affecting both cortical and motor neurons.
FTLD-ALS is characterized by the concurrent or sequential development of frontotemporal dementia symptoms (including behavioral changes, language impairment, and executive dysfunction) and motor neuron disease symptoms (progressive muscle weakness, atrophy, and spasticity)[1]. The condition accounts for approximately 5-15% of all ALS cases and up to 30% of FTLD cases show some evidence of motor neuron involvement[2].
The strongest genetic association for FTLD-ALS is with the C9orf72 gene hexanucleotide repeat expansion, which is found in approximately 25-40% of FTLD-ALS cases[3]. This same expansion is the most common genetic cause of both familial ALS and FTLD.
Other implicated genes include:
The hallmark of FTLD-ALS is TDP-43 proteinopathy. Pathological TDP-43 aggregates are found in:
| Region | Pathological Changes |
|---|---|
| Motor Cortex | TDP-43 inclusions, neuronal loss |
| Spinal Cord | Anterior horn cell loss, gliosis |
| Frontal/Temporal Cortex | TDP-43 inclusions, microvacuolation |
| Hippocampus | TDP-43 in dentate gyrus and CA1 |
The typical disease course involves:
NINDS-ADS criteria require:
FTLD-ALS exists on a spectrum with:
Current trials targeting FTLD-ALS include:
Emerging biomarkers under investigation:
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