The Impact of Sponsored Genetic Testing in 170 Consecutive Consenting Patients With Amyotrophic Lateral Sclerosis: A Single-Site Retrospective Review.

INTRODUCTION/AIMS: Amyotrophic lateral sclerosis (ALS) is often categorized as sporadic (sALS) or familial (fALS) based on the family history. Several recent genetic studies have found disease-causing variants in 50%-85% of patients with fALS and 10%-15% of those with sALS. The aim of our study is to review our clinical experience with sponsored genetic testing (i.e., pharmaceutical company-sponsored and cost-free to patient) since its inception.

METHODS

We reviewed the medical records on all ALS patients seen at our Center who consented to sponsored genetic testing from August 2021 through October 2025.

RESULTS

Of the 170 medical records reviewed, 22 patients (12.9%) tested positive for a disease-causing variant in a known autosomal dominant disorder. Thirteen of 35 patients with fALS (37.1%) were found to have a disease-causing variant, in contrast to 9 of 135 patients (6.7%) with sALS. Of the 22 disease-causing variants found, the following genes were involved in decreasing frequency: C9orf72 11 (50%), SOD1 6 (27.3%), FUS 2 (9.1%), and one each (4.5%) of SQSTM1, TARDBP, and TBK1. Twenty-eight patients (16.5%) harbored 29 variants of uncertain significance (VUS).

DISCUSSION: Results of testing led to medically actionable activities including genetic counseling for patients and at-risk family members with positive results, and treatment (i.e., intrathecal tofersen) for the two patients harboring pathogenic SOD1 variants. The lower diagnostic yields than previously published for fALS and sALS patients likely are related to lower numbers of genes tested in the sponsored genetic panels, and these are expected to improve as more genes are added.