Monograph: Guidelines for Genetic Testing of Peripheral Nerve Disorders
Abstract
Inherited peripheral neuropathies (IPNs) comprise a clinically and genetically heterogeneous group of disorders affecting approximately 1 in 2500 individuals and represent one of the most common inherited neurologic diseases. The rapidly expanding identification of disease-causing genes and the widespread implementation of next-generation sequencing (NGS) have fundamentally transformed the diagnostic evaluation of these disorders. Contemporary molecular testing has substantially increased diagnostic yield, shortened the diagnostic delay, refined disease classification, and strengthened genotype–phenotype correlations. In the United States, NGS-based multigene panels have become the most cost-effective first-line molecular diagnostic approach for most patients with suspected inherited neuropathies, whereas phenotype-directed single-gene testing remains appropriate in selected clinical circumstances and in healthcare systems in which access to comprehensive sequencing is limited. Despite these advances, challenges continue to affect diagnostic accuracy, including interpretation of variants of uncertain significance, detection of copy number variants and repeat expansions, technical limitations associated with highly homologous genomic regions such as SORD, and variability in gene content and analytic performance among commercially available testing platforms. Accurate diagnosis therefore requires integration of clinical phenotype, electrodiagnostic findings, family history, and molecular data. Establishing a precise genetic diagnosis has become increasingly important because it improves prognostic accuracy, guides genetic counseling and cascade testing, identifies patients with treatable hereditary neuropathies such as transthyretin amyloidosis, and facilitates enrollment in gene-specific clinical trials and emerging precision therapies. An evidence-based, phenotype-driven approach that incorporates contemporary molecular technologies is essential to maximize diagnostic efficiency while recognizing the strengths and limitations of currently available genetic testing strategies.
Objectives: The objectives of this activity are to: (1) Recognize the clinical features and electrophysiologic patterns that suggest an inherited peripheral neuropathy and prioritize the appropriate differential diagnosis. (2) Select the most appropriate molecular testing strategy based on clinical phenotype, inheritance pattern, and current evidence regarding diagnostic yield and cost-effectiveness. (3) Integrate genetic test results into the comprehensive evaluation of patients with inherited peripheral neuropathies, recognizing the limitations of current technologies and the importance of multidisciplinary genetic counseling.
ACCREDITATION STATEMENT
The AANEM is accredited by the American Council for Continuing Medical Education (ACCME) to providing continuing education for physicians. AANEM designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
DISCLOSURE INFORMATION
The author is on the advisory commitee and receives honoraria from Roche Genentech and Applied Therapeutics. All relevant financial relationships have been mitigated according to Accreditation Council for Continuing Medical Education standards.
Mario Saporta