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The expansion in the C9orf72 gene has been recently reported as a genetic cause of Huntington's disease (HD) phenocopies. We aim to assess the frequency of the C9orf72 gene expansion in a Portuguese HD phenocopies cohort. Twenty HD phenotype-like patients without diagnosis were identified in our institutional database. C9orf72 gene expansion was detected using repeat-primed PCR. Clinical files were reviewed to characterize the phenotype of expansion-positive cases. One patient (5%) was positive for the C9orf72 expansion. A second patient presented 27 repeats-within the intermediate size interval. Both had familial neuropsychiatric disease characterized by diverse movement disorders, dementia, and psychiatric dysfunction that was distinct in severity and clinical expression. C9orf72 disease is clinically heterogeneous and without evident imaging markers. The definition of the role of intermediate alleles and of the pathological threshold for C9orf72 repeat expansions may have diagnostic implications.

Background and purpose Acquired hepatocerebral degeneration (AHD) and hepatic encephalopathy (HE) are neurological complications of chronic liver disease (CLD) with portosystemic shunt. While HE is common, AHD is a rare entity, and the clinical imaging relationships observed in small series lack validation in large patient cohorts. The aim of this study was to characterize a cohort of AHD patients and to explore possible associations with HE coexistence. Methods We performed a retrospective analysis of patients with a working AHD diagnosis, between 2008 and 2019. Clinical, laboratory, imaging and neuropsychological results at first neurological observation were reviewed and compared between the 'AHD' group and the 'AHD with HE' group. Results A total of 76 patients were recruited. The most frequent neurological manifestations were neuropsychiatric (93.4%) and extrapyramidal (84.2%). Only 38% of patients had hypermanganesemia. Compared with the AHD group, the AHD with HE group had more hyperkinetic movement disorders (71.4% vs. 38.5%; P = 0.05), a higher number of patients on the dementia spectrum (57.7% vs. 20%; P = 0.04), higher median ammonia levels (P = 0.014) and more widespread cortico‐subcortical and pyramidal involvement on brain magnetic resonance imaging. Nineteen patients underwent liver transplantation, with significantly improved survival (P = 0.006). Discussion Hepatic encephalopathy and AHD often coexist in the same patient. Seventy‐six patients with CLD and AHD were evaluated, making this one of the largest reported AHD cohorts. Blood manganese level was a weak diagnostic marker in AHD. Early liver function restoration through liver transplantation improved survival. Our report provides a detailed description of the phenotype and long‐term outcome of AHD, with relevance for diagnosis and treatment.

T2-FLAIR mismatch sign has been advocated to be 100% specific for IDH-mutant 1p/19q non-codeleted gliomas (diffuse astrocytomas). However, false positives have been reported in recent works. Loose application of the criteria may lead to erroneous classification, especially by non-trained neuroradiologists. In this pictorial essay, we aim to bring attention to the need for strict criteria for the application of T2-FLAIR mismatch sign and to discuss the potential pitfalls in the application of these criteria. For that, a series of adult brain tumour cases are presented to demonstrate how to apply this radiological sign in the clinical practice.

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