Ultra-sensitive Quantification of UBE3A in Human CSF Using SISCAPA-MS

Angelman Syndrome (AS) is a rare neurodevelopmental disorder caused by the loss of maternal ubiquitin-protein ligase E3A (UBE3A) expression in neurons, where the paternal allele is silenced by a neuron-specific antisense transcript.

UBE3A encodes a ubiquitin ligase essential for synaptic development and neuronal function. Therapeutic strategies aim to restore UBE3A activity by reactivating the paternal allele or delivering functional protein to the brain. However, quantifying UBE3A in cerebrospinal fluid (CSF) is technically challenging due to its extremely low abundance and the limitations of conventional immunoassays1.

To overcome this, we developed a highly sensitive hybrid assay using Stable Isotope Standards and Capture by Anti-Peptide Antibodies combined with LC-MS (SISCAPA-MS) to quantify UBE3A in CSF.

Here, we present the development and characterization of this assay and demonstrate its application in CSF samples.