Identification of two novel <i>ALS2</i> mutations in infantile-onset ascending hereditary spastic paraplegia

Abstract

Biallelic mutations of ALS2 cause a clinical spectrum of overlapping autosomal recessive neurodegenerative disorders: infantile-onset ascending hereditary spastic paralysis (IAHSP), juvenile primary lateral sclerosis (JPLS), and juvenile amyotrophic lateral sclerosis (ALS2). We report on eleven individuals affected with IAHSP from two consanguineous Pakistani families. A combination of linkage analysis with homozygosity mapping and targeted sequencing identified two novel ALS2 mutations, a c.194T > C (p.Phe65Ser) missense substitution located in the first RCC-like domain of ALS2/alsin and a c.2998delA (p.Ile1000*) nonsense mutation. This study of extended families including a total of eleven affected individuals suggests that a given ALS2 mutation may lead to a phenotype with remarkable intrafamilial clinical homogeneity.