A new MPZ mutation associated with a mild CMT1 phenotype presenting with recurrent nerve compression

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Myelin protein zero (P0) is crucial for myelin structure and function, and mutations in its gene (MPZ) are linked to demyelinating neuropathies.
• Charcot-Marie-Tooth disease type 1B (CMT1B) is a primary demyelinating neuropathy typically caused by MPZ mutations, exhibiting a range of clinical presentations.
• Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent nerve damage at compression sites.

Observation:

• This study details four patients, three from one family, presenting with demyelinating neuropathy.
• Some patients exhibited recurrent nerve lesions at sites of compression, mimicking HNPP.
• A novel heterozygous nonsense mutation, Tyr145Stop (c.435T>A) in exon 3 of the MPZ gene, was identified in all affected individuals.

Findings:

• The identified MPZ Tyr145Stop mutation results in a truncated extracellular P0 protein.
• This specific mutation is associated with a milder phenotype of demyelinating neuropathy.
• The mutation was found in patients presenting with symptoms suggestive of both CMT1B and HNPP.

Implications:

• The findings suggest that MPZ gene analysis should be considered in patients with demyelinating neuropathies, especially those with acute nerve compression or an HNPP phenotype.
• Investigating MPZ mutations is important in cases of HNPP with a normal PMP22 gene.
• This research expands the understanding of genotype-phenotype correlations in MPZ-related neuropathies, highlighting the role of specific mutations in disease severity.