Peripheral neuropathy: why only some mutations cause disease, PgII

Key Highlights:

• Inherited peripheral neuropathies (IPN) affect approximately 1 in 2,500 individuals, causing symptoms like high foot arches and clawed fingers.
• Mutations in over 100 genes, including seven aminoacyl-tRNA synthetase (ARS) genes, can cause IPN.
• Research from the University of Michigan Medical School reveals that disease-causing mutations in ARS genes have a dominant-negative effect.
• The faulty protein interferes with the healthy version, reducing ARS enzyme activity.
• Studies published in Human Molecular Genetics (2023) and Human Genetics and Genomics Advances (January 2026) detail these findings.

Detailed Insights:

• IPN results from mutations that impair nerve function, leading to muscle weakness and sensory loss in the extremities.
• The dominant-negative effect means a mutant protein not only fails to function but also disrupts the function of the normal protein.
• Individuals with a dominant-negative mutation have less ARS enzyme activity than those with a missing gene copy, explaining why some remain healthy while others develop IPN.
• The neuropathy-associated protein pairs with the healthy protein, creating a non-functional dimer, which reduces overall function.
• Experiments using budding yeast (Saccharomyces cerevisiae) helped uncover the dominant-negative effect of neuropathy-associated AARS1 and NARS1 mutations.
• Long nerves in limbs are particularly vulnerable to interference from these mutations due to the distance from the cell's main body.
• Targeting and blocking the mRNA or protein made from the dominant-negative gene could potentially treat IPNs.

Scientific/Technical Concepts Involved:

• Aminoacyl-tRNA synthetases (ARS): Enzymes that attach the correct amino acid to its corresponding tRNA molecule.
• Dominant-negative mutation: A mutation where the faulty protein actively interferes with the function of the healthy protein.
• tRNA (transfer RNA): RNA that delivers amino acids to ribosomes for protein synthesis.
• Ribosomes: Cell structures that function as protein-making factories.