Brain calcification process and phenotypes according to age and sex: Lessons from SLC20A2, PDGFB, and PDGFRB mutation carriers.

Primary Familial Brain Calcification (PFBC) is a dominantly inherited cerebral microvascular calcifying disorder with diverse neuropsychiatric expression. Three causative genes have been identified: SLC20A2, PDGFRB and, recently, PDGFB, whose associated phenotype has not yet been extensively studied. We included in the largest published case series of genetically confirmed PFBC, 19 PDGFB (including three new mutations), 24 SLC20A2 (including 4 new mutations), and 14 PDGFRB mutation carriers, from two countries (France and Brazil). We studied clinical features and applied our visual rating scale on all 49 available CT scans. Among the symptomatic mutation carriers (33/57, 58%), the three most frequently observed categories of clinical features were psychiatric signs (72.7%, 76.5%, and 80% for PDGFB, SLC20A2, and PDGFRB, respectively), movement disorders (45.5%, 76.5%, and 40%), and cognitive impairment (54.6%, 64.7%, and 40%). The median age of clinical onset was 31 years, 25% had an early onset (before 18) and 25% a later onset (after 53). Patients with an early clinical onset exhibited mostly isolated psychiatric or cognitive signs, while patients with a later onset exhibited mostly movement disorders, especially in association with other clinical features. CT scans rating allowed identifying four patterns of calcification. The total calcification score was best predicted by the combined effects of gene (SLC20A2 > PDGFB > PDGFRB mutations), sex (male), and (increasing) age, defining three risk classes, which correlated with the four patterns of calcification. These calcification patterns could reflect the natural history of the calcifying process, with distinct risk classes characterized by different age at onset or rate of progression.

Searching for new genetic risk factors for neuropsychiatric disorders in expression databases.

Genetic variations might contribute to differences in protein activities and gene expression levels observed in complex genetic traits, like neuropsychiatric disease. This finding motivated the development of original approaches using expression studies to guide the finding of new genetic variations. We extended this approach to new genes selected from microarrays studies of brain samples of patients with Alzheimer's disease, major depressive disorder, bipolar affective disorder, and sporadic Creutzfeldt-Jakob disease. The CLCbio Workbench Combined version 3.6.2 was initially used to build expression sites tags (ESTs) and mRNA files retrieved, respectively, from the Goldenpath (UCSC) and NCBI databases and latter to perform multiple batches of Smith-Waterman alignments. The total of 438 ESTs sequences were selected after proper stringent parameters were applied to the first set of mismatches. The annotation revealed various classes of variations, most of them deletions ranging from 1 to 10 pb. These deletions were present in coding regions, 5' and 3' UTR regions. Deletions are often associated to major genetic syndromes with dysmorphic features; however, recent studies show that common microdeletions might be highly associated with common neuropsychiatric disorders.