ALS and fertility: does ALS affect number of children patients have?

Amyotrophic Lateral Sclerosis is one major disease in the group of neurodegenerative conditions. As with most other neurodegenerative diseases, clinical signs of the disease usually show among the elderly population, and most commonly around 60-65 years of age. Therefore the disease is not expected to impact the fertility of ALS patients. When examined from an evolutionary medicine and evolutionary biology perspective, there should be no selection pressure on the patient population due to the late onset of ALS. Methods: In this study, we tested the hypothesis that ALS does not affect fertility on a group of patients with ALS that we collected in a multi-center study. We recruited 511 patients diagnosed with ALS according to the revised El Escorial criteria, and 236 control cases without a neurodegenerative disease. We compared the ALS group's number of offspring with the control group in three consecutive generations. Results: No statistically significant difference was found between the number of siblings of ALS and control groups (p = 0.44). A statistically significant difference was found between the number of children of ALS and control groups (p < 0.001), indicating ALS patients had more children than controls. When the number of children is assessed by gender, for women, there was no statistically significant difference between the number of children of ALS and control groups (p = 0.067). Conclusions: This finding supports the view that ALS does not have a negative selection pressure on the patient population's fertility.