Differential Diagnosis of Acquired and Hereditary Neuropathies in Children and Adolescents-Consensus-Based Practice Guidelines

Early Onset Inherited Peripheral Neuropathies: The Experience of a Specialized Referral Center for Genetic Diagnosis Achievement

BACKGROUND

Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of inherited peripheral neuropathies. Although the typical disease onset is reported in the second decade, earlier onsets are not uncommon. To date, few studies on pediatric populations have been conducted and the achievement of molecular diagnosis remains challenging.

METHODS

During the last 24 years we recruited 223 patients with early-onset hereditary peripheral neuropathies (EOHPN), negative for PMP22 duplication, 72 of them referred by a specialized pediatric hospital. Genetic testing for CMT-associated genes has been carried out with a range of different techniques.

RESULTS

Of the 223 EOHPN cases, 43% were classified as CMT1 (demyelinating), 49% as CMT2 (axonal), and 8% as CMTi (intermediate). Genetic diagnosis was reached in 51% of patients, but the diagnostic yield increased to 67% when focusing only on cases from the specialized pediatric neuromuscular centers. Excluding PMP22 rearrangements, no significant difference in diagnostic rate between demyelinating and axonal forms was identified. De novo mutations account for 38% of cases.

CONCLUSIONS

This study describes an exhaustive picture of EOHPN in an Italian referral genetic center and analyzes the molecular diagnostic rate of a heterogeneous cohort compared with one referred by a specialized pediatric center. Our data identify MPZ, MFN2, GDAP1, and SH3TC2 genes as the most frequent players in EOHPN. Our study underlines the relevance of a specific neurological pediatric expertise to address the genetic testing and highlights its importance to clarify possible unexpected results when neuropathy is only a secondary clinical sign of a more complex phenotype.

What is the Next Step after an Electrodiagnostic Study in Children with Polyneuropathies? Rationale for Laboratory and Other Diagnostic Tests

The etiology of polyneuropathies varies in the pediatric population, where hereditary or metabolic disorders are far more common than in adults. However, treatable polyneuropathies, also prevalent in these settings, are those to prioritize. Moreover, diagnosing subacute and chronic symptoms in children can be challenging compared to adults. Therefore, selecting the best and most relevant laboratory investigations and paraclinical studies is critical. This taskcan be relatively challenging in countries with limited resources or insurance coverage. This study describe the various types of polyneuropathies found in children and their characteristics and suggest an algorithm for using the best laboratory tests in the context of the Iranian healthcare system.