New Gene Variant Linked to Familial Parkinson’s

Researchers have discovered a new genetic variant—called p.[Leu119Pro; Leu488Pro]—in the LRRK2 gene in a family affected by inherited Parkinson’s disease. This variant appears to play a role in how the disease develops, even though it is located far from the parts of the gene traditionally linked to Parkinson’s. 🔍 What Makes This Variant Unique? This variant changes the ARM domain of the LRRK2 protein, a part important for the protein’s shape and activity. While many Parkinson’s-related LRRK2 variants boost the protein's function in its "active" sites, this one seems to change the protein’s structure in a way that increases its activity indirectly, by affecting how it interacts with other cellular proteins. ⚙️ How It Affects the Brain Lab tests showed that the new variant increases the interaction between LRRK2 and a protein called RAB8A, but not with a similar protein called RAB10. This difference matters because RAB8A and RAB10 play opposite roles in how cells manage waste and repair damage, especially in mitochondria and lysosomes—areas already linked to Parkinson’s. 🧪 Deeper Findings from Computer Models Computer simulations confirmed that this variant strengthens the bond between LRRK2 and RAB8A. Interestingly, the most significant structural changes were tied to just one part of the variant—Leu119Pro—which has also been found more often in Spanish Parkinson’s patients. The results suggest that this double mutation may have a stronger effect than either mutation alone. 🧠 Clues from Family History and Brain Tissue Some family members carried both the LRRK2 variant and a second genetic deletion in the GBA1 gene, which is known to worsen symptoms and lead to faster cognitive decline in Parkinson’s. Interestingly, one relative without the GBA1 deletion had a milder form of the disease. Also notable: no Lewy bodies (a hallmark of classic Parkinson’s) were found in the brain of the index case. Instead, Alzheimer-type changes were present—a pattern that has been seen in other LRRK2-related Parkinson’s cases. 👥 What This Means for Families Several younger family members who carry the new LRRK2 variant currently show no symptoms, which aligns with the fact that some LRRK2 mutations take time to cause disease. These individuals may be "asymptomatic carriers", and ongoing monitoring could help reveal when and how symptoms might begin. 🧪 Why This Study Matters Although the study involved a small number of people, it combined genetic, lab-based, and computer modeling approaches to suggest that the p.[Leu119Pro;Leu488Pro] variant is likely harmful. More research is needed, especially to understand how this and similar mutations might guide personalized treatments for Parkinson’s. 📌 Final Takeaway This study adds to our understanding of rare LRRK2 mutations and their effects on Parkinson’s disease. It highlights the importance of looking beyond the most well-known mutations and considering how different parts of the LRRK2 gene can impact brain health—and future therapies.