To determine the diagnostic yield of genetic testing in a tertiary neuromuscular clinic ( Nerve and Muscle Center of Texas, NMCT).

Genetic testing is an effective and reliable modality in clinical neuromuscular diagnosis. Both single-gene sequencing and next-generation sequencing are widely used among neuromuscular clinicians due to their value in identifying many neuromuscular disorders. The recent developments in testing methods and increasing reliance on genetic testing in clinical practice require more studies to examine the benefits of such tests.

We examined the results of single-gene sequencing/repeat analysis,  gene panels, and whole-exome sequencing (WES) of 514 tests of 393 patients performed in the period of 2014-2020. The results were either positive, negative, or variants of uncertain significance (VUS) and were categorized by disease type and test type. When a patient had more than one test done as a  result of negative test prompting further investigation, we analyzed the results to examine the consecutive testing validity and usefulness. All patient were suspected of a neuromuscular disorder and the samples were either WBC or muscle tissue.

28.60% (n.147) of the tests were positive while 23.74% (n.122) were VUS. In single-gene sequencing/repeat analysis, 43.08% were positive, in panels, 23.17% were positive, while 30.00% were positive in WES. Regarding disease type; we observed a 38.68% positive rate for myopathy, 19.64% positive rate for neuropathy, 18.18% positive rate for Motor Neuron Disease, and 26.67% positive rate for the rest if disorders.

Our results showed consistency with current studies and the improvement trends of genetic testing results over time. Although some obstacles are identified, the benefits of genetic testing are obvious both to patients and public health. Providing statistical data can support more usage and popularity of genetic testing among physicians.