Distinct clinical and neuropathological features of G51D SNCA mutation cases compared with SNCA duplication and H50Q mutation

Background: We and others have described the neurodegenerative disorder caused by G51D SNCA mutation which shares characteristics of Parkinson’s disease (PD) and multiple system atrophy (MSA). The objective of this investigation was to extend the description of the clinical and neuropathological hallmarks of G51D mutant SNCA-associated disease by the study of two additional cases from a further G51D SNCA kindred and to compare the features of this group with a SNCA duplication case and a H50Q SNCA mutation case. Results: All three G51D patients were clinically characterised by parkinsonism, dementia, visual hallucinations, autonomic dysfunction and pyramidal signs with variable age at disease onset and levodopa response. The H50Q SNCA mutation case had a clinical picture that mimicked late-onset idiopathic PD with a good and sustained levodopa response. The SNCA duplication case presented with a clinical phenotype of frontotemporal dementia with marked behavioural changes, pyramidal signs, postural hypotension and transiently levodopa responsive parkinsonism. Detailed post-mortem neuropathological analysis was performed in all cases. All three G51D cases had abundant α-synuclein pathology with characteristics of both PD and MSA. These included widespread cortical and subcortical neuronal α-synuclein inclusions together with small numbers of inclusions resembling glial cytoplasmic inclusions (GCIs) in oligodendrocytes. In contrast the H50Q and SNCA duplication cases, had α-synuclein pathology resembling idiopathic PD without GCIs. Phosphorylated α-synuclein was present in all inclusions types in G51D cases but was more restricted in SNCA duplication and H50Q mutation. Inclusions were also immunoreactive for the 5G4 antibody indicating their highly aggregated and likely fibrillar state. Conclusions: Our characterisation of the clinical and neuropathological features of the present small series of G51D SNCA mutation cases should aid the recognition of this clinico-pathological entity. The neuropathological features of these cases consistently share characteristics of PD and MSA and are distinct from PD patients carrying the H50Q or SNCA duplication

Bone-Specific Alkaline Phosphatase In Patients Who Have Undergone The Fontan Operation

Bone-specific alkaline phosphatase (BALP) is produced by osteoblasts. A recent series noted a positive association between cardiac index (CI) and BALP in patients with Fontan circulation. CI is low at baseline in these patients, and small decreases in CI may result in diverting of blood away from bone. We prospectively enrolled 15 patients (males ≤ 14 yo, females ≤ 12 yo) who had previously undergone Fontan operation and were undergoing cardiac catheterization. Serum BALP was measured at catheterization, and analysis performed to evaluate association between age-/gender-specific BALP z-score and CI as well as other patient variables. The median age at catheterization was 5.6 years (3.1–13.1), and time from Fontan was 1.5 years (0.1–12.1). The median superior vena cava saturation (SVC) was 65 % (52–74), median average between SVC and inferior vena cava (IVC) saturations was 62.5 % (51–70), and median CI was 3.8 L/min/m2 (2.0–8.4). The median BALP was 65 IU/L and BALP z-score was −2.1 (−3.2 to 0.9). BALP z-score was not associated with CI (ρ = −0.1, p = 0.7), but a positive correlation was noted with the average of SVC and IVC saturation (ρ = 0.5, p = 0.052) and with SVC saturation (ρ = 0.4, p = 0.07), both nearly reaching statistical significance. In our cohort of children with Fontan circulation undergoing catheterization, BALP z-score was not associated with CI, but an association with estimates of mixed venous saturation was noted that nearly reached statistical significance. We hypothesize that BALP is a marker of oxygen delivery in those with Fontan circulation and may represent a valuable biomarker in this population