# Clinical and Sociodemographic Profile of Familial Amyotrophic Lateral Sclerosis Type 8 Compared to the Sporadic Form

## TL;DR

This study compares the clinical and demographic features of familial ALS type 8 with sporadic ALS in Brazil, finding differences in age at diagnosis, symptom onset, and disease progression.

## Contribution

The study provides new insights into the distinct clinical profile of familial ALS type 8 in a South American population.

## Key findings

- fALS8 patients were diagnosed at a younger age compared to sALS patients.
- fALS8 showed lower limb onset predominance, while sALS had more varied symptom onset.
- Older age at diagnosis was linked to worse functional outcomes in sALS patients.

## Abstract

Amyotrophic lateral sclerosis (ALS) is a rare degenerative disease of motor neurons, predominantly sporadic, with approximately 10% of the cases showing familial inheritance.

To characterize the clinical and sociodemographic profile of patients with familial ALS type 8 (fALS8) and compare it with sporadic ALS (sALS).

We reviewed the medical records (1997–2022) from a specialized Brazilian center. Patients with a confirmed diagnosis of ALSs were included, and sociodemographic and clinical data were collected.

The sample was composed of 89 ALS patients, with a slight female predominance (53%) and a high frequency of fALS8 cases (45%). The fALS8 patients were diagnosed at a younger age, at approximately 50 years, compared to 53 years among the sALS patients (
p
 = 0.043). Lower limb onset predominated in the fALS8 group (87%), while the sALS group showed more heterogeneous presentations, including bulbar onset (14%). The time until the diagnosis was significantly longer in the fALS8 group compared to the sALS group, both from symptom onset (approximately 51 versus 30 months respectively;
p
 < 0.001) and after admission to a specialized center (7 versus 4 months respectively;
p
 = 0.002). Dysphagia and gastrostomy were more frequent in the sALS group compared to the fALS8 group (
p
 = 0.02 and
p
 < 0.01 respectively), and older age at diagnosis was associated with worse functional scores.

The fALS8 group presented with distinct clinical and demographic features compared to the sALS group, including younger age at diagnosis, more homogeneous symptom onset, and lower frequency of dysphagia and need for gastrostomy. The diagnosis was more delayed in the fALS8 group, and older age at diagnosis was associated with worse functional status. The current study contributes to the scarce data on fALS8 in South America.