The most common genetic risk factor for Parkinson's disease known is a damaging variant in the GBA1 gene. The entire GBA1 gene has rarely been studied in a large cohort from a single population. The objective of this study was to assess the entire GBA1 gene in Parkinson's disease from a single large population.

A mutation in the GBA1 gene is the most common genetic risk factor for developing Parkinson's disease. GBA1 encodes the lysosomal enzyme glucosylceramidase beta (glucocerebrosidase, GCase) and mutations decrease enzyme activity. LTI-291 is an allosteric modulator of GCase, enhancing its activity. These first-in-human studies evaluated the safety, tolerability, pharmacokinetics and pharmacodynamics of single and multiple ascending doses of LTI-291 in healthy volunteers.

A variant in the GBA1 gene is one of the most common genetic risk factors to develop Parkinson's disease (PD). Here the serendipitous finding is reported of a polymerase dependent allelic imbalance when using next generation sequencing, potentially resulting in false-negative results when the allele frequency falls below the variant calling threshold (by default commonly at 30%). The full GBA1 gene was sequenced using next generation sequencing on saliva derived DNA from PD patients. Four polymerase chain reaction conditions were varied in twelve samples, to investigate the effect on allelic imbalance: (1) the primers (n = 4); (2) the polymerase enzymes (n = 2); (3) the primer annealing temperature (Ta) specified for the used polymerase; and (4) the amount of DNA input. Initially, 1295 samples were sequenced using Q5 High-Fidelity DNA Polymerase. 112 samples (8.6%) had an exonic variant and an additional 104 samples (8.0%) had an exonic variant that did not pass the variant frequency calling threshold of 30%. After changing the polymerase to TaKaRa LA Taq DNA Polymerase Hot-Start Version: RR042B, all samples had an allele frequency passing the calling threshold. Allele frequency was unaffected by a change in primer, annealing temperature or amount of DNA input. Sequencing of the GBA1 gene using next generation sequencing might be susceptible to a polymerase specific allelic imbalance, which can result in a large amount of flase-negative results. This was resolved in our case by changing the polymerase. Regions displaying low variant calling frequencies in GBA1 sequencing output in previous and future studies might warrant additional scrutiny.