Identification of novel FUS and TARDBP gene mutations in Chinese amyotrophic lateral sclerosis patients with HRM analysis

An Atypical Presentation of Upper Motor Neuron Predominant Juvenile Amyotrophic Lateral Sclerosis Associated with TARDBP Gene: A Case Report and Review of the Literature

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that can rarely affect young individuals. Juvenile ALS (JALS) is defined for individuals with an onset of the disease before the age of 25. The contribution of genetics to ALS pathology is a field of growing interest. One of the differences between adult-onset ALS and JALS is their genetic background, with a higher contribution of genetic causes in JALS. We report a patient with JALS and a pathogenic variant in the TARDBP gene (c.1035C > G; p.Asn345Lys), previously reported only in adult-onset ALS, and with an atypical phenotype of marked upper motor neuron predominance. In addition, the proband presented an additional variant in the NEK1 gene, c.2961C > G (p.Phe987Leu), which is classified as a variant of unknown significance. Segregation studies showed a paternal origin of the TARDBP variant, while the variant in NEK1 was inherited from the mother. We hypothesize that the NEK1 variant acts as a disease modifier and suggests the possibility of a functional interaction between both genes in our case. This hypothesis could explain the peculiarities of the phenotype, penetrance, and the age of onset. This report highlights the heterogeneity of the phenotypic presentation of ALS associated with diverse pathogenic genetic variants.

Genotype-phenotype association of TARDBP mutations in Chinese patients with amyotrophic lateral sclerosis: a single-center study and systematic review of published literature

BACKGROUND

This study aims to determine the genetic and clinical features of TARDBP-mutated patients in our cohort of Chinese patients with amyotrophic lateral sclerosis (ALS) combined with data in the literature.

METHODS

We performed TARDBP mutation screening in 1258 Chinese ALS patients, including 1204 sporadic ALS (sALS) and 54 familial ALS (fALS) patients. A systematic literature review was conducted by searching TARDBP-mutated patients from China in the online databases.

RESULTS

In our cohort, the mutant frequency of TARDBP variants was 0.3% (4/1258), with two recurrent variants (p.G294V, p.G298V) and one novel variant (p.S332G) identified. Combining with data in the literature review, the TARDBP-mutant frequency in the Chinese population was 1.4% (83/5998), with 0.8% (46/5470) in sALS and 7.0% (37/528) in fALS. Most patients had limb onset (63.0%), with an average life expectancy of 4.3 years (range 0.5-13). Disease durations significantly differed (p = 0.002), with p.M337V showing the longest duration (80 months) and p.N378D showing the shortest duration (16.7 months).

CONCLUSION

Our study found that TARDBP mutation was not rare in Chinese fALS patients. Different TARDBP mutations were associated with specific features in phenotypes.