Quantitative dopamine transporter imaging assessment in Parkinson's disease patients carrying GBA gene mutations compared with idiopathic PD patients: A case‐control study

BACKGROUND: Genetic risk factors impact around 15% of Parkinson's disease (PD) patients and at least 23 variants have been identified including Glucocerebrosidase (GBA) gene variants. Using different clinical and instrumental qualitative‐based data, various studies have been published on GBA‐PD cohorts which suggested possible differences in dopaminergic nigrostriatal denervation pattern, particularly in caudate and putamen nuclei. METHODS: This retrospective study included two consecutive homogenous cohorts of GBA‐PD and idiopathic (I‐PD) patients. Each consecutive GBA‐PD patient has been matched with a 1:1 pairing method with a consecutive I‐PD subject according to age, age at disease onset, sex, Hoehn & Yahr (H&Y) staging scale and comorbidity level (CCI). Semiquantitative volumetric data by the DaTQUANT(TM) software integrated in the DaTSCAN exam performed at time of the diagnosis (SPECT imaging performed according to current guidelines of I‐123 FPCIT SPECT imaging) were extrapolated. Bilateral specific binding ratios (SBR) at putamen and caudate levels were calculated, using the occipital lobes uptake. The Mann–Whitney test was performed to compare the two cohorts while the Spearman's test was used to find correlations between motor and volumetric data in each group. Bonferroni correction was used to account for multiple comparisons. RESULTS: Two cohorts of 25 patients each (GBA‐PD and I‐PD), were included. By comparing GBA‐PD and I‐PD patients, lower SBR values were found in the most affected anterior putamen and left caudate of the GBA‐PD cohort. Furthermore, in the GBA‐PD cohort the SBR of the most affected posterior putamen negatively correlated with the H&Y scale. However, none of these differences or correlations remained significant after Bonferroni correction for multiple comparisons. CONCLUSIONS: We observed differences in SBR values in GBA‐PD patients compared with I‐PD. However, these differences were no longer significant after Bonferroni multiple comparisons correction highlighting the need for larger, longitudinal studies.