RT @davidcapple: Big thanks to @fishmanaf for inviting me to join him on the Startup Dad podcast. This conversation was deeply personal an….

RT @davidcapple: 𝗜𝗻𝘁𝗿𝗼𝗱𝘂𝗰𝗶𝗻𝗴 @SharkToothBio: 𝗔 𝗣𝗲𝗿𝘀𝗼𝗻𝗮𝗹 𝗠𝗶𝘀𝘀𝗶𝗼𝗻 𝘁𝗼 𝗖𝗼𝗺𝗯𝗮𝘁 𝗖𝗠𝗧𝟭𝗔. 2 years ago, my world was flipped upside down. My 2-year-o….

This 2024 study reveals that boosting cGMP with drugs like tadalafil or CYR119 improves proteostasis, myelination, and nerve conduction in mouse models of #CMT1A & #CMT1B. Promising steps toward potential treatments!.

Grateful to Effie (@OnceUponAGene) for this great episode about choosing friends as rare disease parents 👇. Highlights:.- Find your people.- Remember who you were before rare disease.- Be intentional.

Interesting targeting approach: Antibody-targeted chromatin delivers CRISPR/Cas9 efficiently into cells. High precision, low toxicity, and no viral components. Could this be applicable to CMT1A?.

Fascinating treatment for SMA 👇. EVRYSDI is a small molecule taken daily. It modifies SMN2 gene splicing by binding to SMN2 mRNA and results in increasing the production of the life-saving SMN protein. Wondering if it could be engineered to bind to PMP22 mRNA….

Boosting cGMP levels with sildenafil restores proteasome function, reduces proteotoxic stress, & improves myelination in a mouse model of CMT1B. This could also work for CMT1A.

This paper shows that we can measure a 1.55x increase in PMP22 from CMT1A skin biopsies. This implies that skin biopsies can be used to accurately measure a (future) treatment's ability to downregulate the body's production of PMP22.

The combination of these processes explains why CMT1A can present with early-onset symptoms that progressively worsen over time. The initial poor quality of myelin affects nerve function early in life, and continued damage to this already weak myelin exacerbates the condition.

Demyelinating vs. Dysmyelinating? From our reading so far it appears that CMT1A is a combination of both. Initially, myelin is improperly formed (dysmyelination). Over time, this already defective myelin becomes further damaged and degraded (demyelination).

Note: this study was performed on CMT1 patients (both CMT1A and 1B). Unfortunately it does not differentiate between the two groups so it's unknown how many were 1A vs. 1B.

Interesting chart of nerve conduction velocity over time in 107 patients with CMT.(Source:

Excessive PMP22 disrupts the delicate balance of lipid-to-protein ratio required for proper myelin structure. This imbalance leads to the formation of disordered myelin-like assemblies, contributing to the defective myelin in CMT1A.

Note: there are concerns with AAV (viral vectors) delivery:.1) Since CMT1A is non-lethal, the risk-reward might not be there for some patients. 2) Taking an AAV treatment now might preclude patients from taking a safer AAV treatment in the future.

This study concludes that AAV2/9 gene therapy is an effective approach for treating CMT1A by reducing PMP22 overexpression in Schwann cells. This approach maintained motor and sensory functions in animal models over an extended period.

Note: this is not the same delivery as LNPs. Squalenoyl siRNA: chemical conjugation of siRNA to squalene, leading to self-assembly into nanoparticles. LNPs: encapsulation of siRNA within a lipid matrix, without direct chemical bonding between the siRNA and lipid components.

This study demonstrates that squalenoyl siRNA PMP22 nanoparticles treat CMT1A in mice, offering hope for developing a similar therapeutic approach for human patients.

Evidence suggests that CMT1A involves developmental defects in myelination, leading to uniformly slowed nerve conduction, rather than active demyelination. This insight challenges traditional views and impacts therapeutic approaches.

Is CMT1A demyelinating or dysmyelinating?.