SOD1 D91A variant in the southernmost tip of Europe: a heterozygous ALS patient resident on the island of Gozo.

Amyotrophic lateral sclerosis (ALS) is frequently caused by mutations in the SOD1 gene. Here, we report the first SOD1 variant in Malta, an archipelago of three inhabited islands in southern Europe. We describe a patient with a sporadic form of ALS living on the island of Gozo in which the heterozygous SOD1 c.272A>C; p.(Asp91Ala) variant was detected. The patient had a late onset (79 years), sensory impairments and rapid disease progression culminating in respiratory failure. ALS has not yet developed in any of the three additional family members in which the D91A variant was identified. None of the healthy controls from the Maltese population were found to carry this variant. This report underscores the high prevalence of the D91A variant in Europe, despite the presence of a North-South gradient in its frequency, and confirms that this variant can be associated with dominant cases in Mediterranean countries.