ALS-plus related clinical and genetic study from China

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder. An increasing number of researchers have found extra motor features in ALS, which are also called ALS-plus syndromes. Besides, a great majority of ALS patients also have cognitive impairment. However, clinical surveys of the frequency and genetic background of ALS-plus syndromes are rare, especially in China.

METHODS

We investigated a large cohort of 1015 patients with ALS, classifying them into six groups according to different extramotor symptoms and documenting their clinical manifestations. Meanwhile, based on their cognitive function, we divided these patients into two groups and compared demographic characteristics. Genetic screening for rare damage variants (RDVs) was also performed on 847 patients.

RESULTS

As a result, 16.75% of patients were identified with ALS-plus syndrome, and 49.5% of patients suffered cognitive impairment. ALS-plus group had lower ALSFRS-R scores, longer diagnostic delay time, and longer survival times, compared to ALS pure group. RDVs occurred less frequently in ALS-plus patients than in ALS-pure patients (P = 0.042) but showed no difference between ALS-cognitive impairment patients and ALS-cognitive normal patients. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus symptoms than ALS-cognitive normal group (P = 0.001).

CONCLUSION

In summary, ALS-plus patients in China are not rare and show multiple differences from ALS-pure patients in clinical and genetic features. Besides, ALS-cognitive impairment group tends to harbour more ALS-plus syndrome than ALS-cognitive normal group. Our observations correspond with the theory that ALS involves several diseases with different mechanisms and provide clinical validation.

Mutation spectrum of amyotrophic lateral sclerosis in Central South China

To analyze the mutational spectrum of known ALS causative genes in China ALS patients. We comprehensively analyzed 51 ALS causative genes by combining different sequencing technologies in 753 unrelated ALS patients from Central South China. The mean age at onset (AAO) was 53.7±11.4 years. The AAO was earlier in the autosomal dominant (AD) ALS patients than in the sporadic ALS (sALS) patients. Bulbar onset was more frequent in females than in males. SOD1 was the most frequently mutated gene in the AD-ALS and the sALS patients, followed by the ATXN2 and FUS genes in the AD-ALS patients and the NEK1 and CACNA1H genes in the sALS patients. Patients with RDVs in the SOD1 or FUS genes had an earlier AAO than the mean AAO of all the patients, while the patients with RDVs in the NEK1 gene showed later onset. SOD1 gene was the most commonly mutated gene in ALS patients in China, followed by ATXN2 and NEK1. The phenotype might be determined synergistically by sex and genetic variants.