Mutational analysis and genotype/phenotype correlation in Turkish Charcot-Marie-Tooth Type 1 and HNPP patients

Area of Science:

• Neurogenetics
• Molecular Biology
• Clinical Neurology

Background:

• Charcot-Marie-Tooth Type 1 (CMT1) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) are often linked to genetic alterations in the 17p11.2 region.
• Previous studies identified point mutations in PMP22, MPZ, and Cx32 genes in CMT1 and PMP22 in HNPP patients lacking deletions.

Purpose of the Study:

• To investigate mutations in PMP22 and Cx32 genes in Turkish patients diagnosed with CMT1 and HNPP, specifically those without large deletions or duplications.
• To correlate identified genetic mutations with the clinical presentation and severity of these peripheral neuropathies.

Main Methods:

• Genetic screening of PMP22 and Cx32 genes was performed on DNA samples from 54 CMT1 patients and 25 HNPP patients from Turkey.
• Mutation analysis included sequencing of coding regions and flanking intronic sequences of the target genes.
• Clinical data and phenotypes of the patients were collected and analyzed in conjunction with genetic findings.

Main Results:

• A novel frameshift mutation in the PMP22 gene was identified in an HNPP patient.
• A point mutation in the PMP22 gene was detected in a CMT1 patient.
• Two distinct point mutations in the Cx32 gene were found in two CMTX patients, and a polymorphism was identified in another patient.

Conclusions:

• The study identified novel PMP22 and Cx32 gene mutations in Turkish patients with CMT1 and HNPP, expanding the spectrum of known mutations.
• The identified mutations and polymorphism in PMP22 and Cx32 genes correlate with the clinical phenotypes observed in the patients.
• These findings contribute to a better understanding of the genetic basis of CMT1 and HNPP and emphasize the importance of genetic testing in diagnosis and management.