Alu Retrotransposition Event in SPAST Gene as a Novel Cause of Hereditary Spastic Paraplegia

ObjectivesTo diagnose the molecular cause of hereditary spastic paraplegia (HSP) observed in a four-generation family with autosomal dominant inheritance. MethodsMultiplex ligation-dependent probe amplification (MLPA), whole-exome sequencing (WES), and RNA sequencing (RNA-seq) of peripheral blood leukocytes were performed. Reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing were used to characterize target regions of SPAST. ResultsA 121-bp AluYb9 insertion with a 30-bp poly-A tail flanked by 15-bp direct repeats on both sides was identified in the edge of intron 16 in SPAST that segregated with the disease phenotype. ConclusionsWe identified an intronic AluYb9 insertion inducing splicing alteration in SPAST causing pure HSP phenotype that was not detected by routine WES analysis. Our findings suggest RNA-seq is a recommended implementation for undiagnosed cases by first-line diagnostic approaches. & COPY; 2023 International Parkinson and Movement Disorder Society.

Automated summary

The molecular cause of hereditary spastic paraplegia (HSP) in a four-generation family with autosomal dominant inheritance was diagnosed using MLPA, WES, and RNA-seq. An intronic AluYb9 insertion in the edge of intron 16 in SPAST was identified, which segregated with the disease phenotype. Our findings suggest that RNA-seq is a recommended first-line diagnostic approach for undiagnosed cases.