Clinical significance of SQSTM1 variants in ALS: report of p.Arg119Cys and literature review

We analyzed the clinical features of a patient with amyotrophic lateral sclerosis (ALS) carrying a novel variant in the sequestosome 1 (SQSTM1) gene and explored the genotype-phenotype association of SQSTM1 gene variants in combination with previous literature. Clinical data and genetic testing results of an ALS patient treated at our hospital were collected. Whole-exome sequencing was used to screen for ALS-related genes, and candidate variants were validated by Sanger sequencing and family analysis. A systematic search was conducted in the PubMed database using the keywords ("amyotrophic lateral sclerosis") OR ("motor neuron disease") AND ("SQSTM1") to summarize the clinical and genetic characteristics of previously reported ALS patients with SQSTM1 variants. The patient was a 49-year-old male with progressive weakness in both lower limbs for one year and weakness in the left upper limb for the past three months. Electromyography showed extensive neurogenic damage. Genetic testing identified a novel heterozygous missense variant, c.355 C > T (p.Arg119Cys), in the SQSTM1 gene. Family verification revealed that his phenotypically normal mother carried the same variant. The literature search identified 58 cases of ALS associated with SQSTM1 variants. Missense variants were the most common type. We identified a novel SQSTM1 variant, c.355 C > T (p.Arg119Cys), in a ALS patient. Although this finding expands the variant spectrum, its pathogenicity remains uncertain and requires further functional validation and pedigree confirmation. Our literature review further shows that SQSTM1-associated ALS predominantly presents with limb onset, with a subset of patients exhibiting frontotemporal dementia or Paget's disease.