We recently described a disorder termed Huntington disease-like 2 (HDL2) that completely segregates with an unidentified CAG/CTG expansion in a large pedigree (W). We now report the cloning of this expansion and its localization to a variably spliced exon of JPH3 (encoding junctophilin-3), a gene involved in the formation of junctional membrane structures.

BACKGROUND & AIMS Hepatitis C virus (HCV) predominantly infects hepatocytes, but many hepatocytes are not infected; studies have shown that HCV antigens cluster within the liver. We investigated spatial distribution and determinants of HCV replication in human liver samples. METHODS We analyzed liver samples from 4 patients with chronic HCV infection (genotype 1, Metavir scores 0–1) to estimate the proportion of infected hepatocytes and the amount of HCV viral RNA (vRNA) per cell. Single-cell laser capture microdissection was used to capture more than 1000 hepatocytes in grids, to preserve geometric relationships. HCV vRNA and interferon-induced transmembrane protein 3 (IFITM3) messenger RNA (the transcript of an interferon-stimulated gene) were measured in the same hepatocytes by quantitative polymerase chain reaction and assembled in maps to identify areas of high and low HCV replication. RESULTS Patients’ serum levels of HCV RNA ranged from 6.87 to 7.40 log10 IU/mL; the proportion of HCV-infected hepatocytes per person ranged from 21% to 45%, and the level of vRNA ranged from 1 to 50 IU/hepatocyte. Infection was not random; we identified clustering of HCV-positive hepatocytes using infected-neighbor analysis (P < .0005) and distance to the kth nearest neighbor compared with random distributions, obtained by bootstrap simulations (P < .02). Hepatocytes that expressed IFITM3 did not appear to cluster and were largely HCV negative. CONCLUSIONS We used single-cell laser capture and high-resolution analysis to show that in human liver HCV infects hepatocytes in nonrandom clusters, whereas expression of antiviral molecules is scattered among hepatocytes. These findings show that quantitative single-cell RNA measurements can be used to estimate the abundance of HCV vRNA per infected human hepatocyte and are consistent with cell–cell propagation of infection in the absence of clustered IFITM3.

Huntington's disease (HD) is an autosomal dominant disorder characterized by abnormalities of movement, cognition, and emotion and selective atrophy of the striatum and cerebral cortex. While the etiology of HD is known to be a CAG trinucleotide repeat expansion, the pathways by which this mutation causes HD pathology remain unclear. We now report a large pedigree with an autosomal dominant disorder that is clinically similar to HD and that arises from a different CAG expansion mutation. The disorder is characterized by onset in the fourth decade, involuntary movements and abnormalities of voluntary movement, psychiatric symptoms, weight loss, dementia, and a relentless course with death about 20 years after disease onset. Brain magnetic resonance imaging scans and an autopsy revealed marked striatal atrophy and moderate cortical atrophy, with striatal neurodegeneration in a dorsal to ventral gradient and occasional intranuclear inclusions. All tested affected individuals, and no tested unaffecteds, have a CAG trinucleotide repeat expansion of 50 to 60 triplets, as determined by the repeat expansion detection assay. Tests for the HD expansion, for all other known CAG expansion mutations, and for linkage to chromosomes 20p and 4p were negative, indicating that this mutation is novel. Cloning the causative CAG expansion mutation for this new disease, which we have termed Huntington's disease-like 2, may yield valuable insight into the pathogenesis of HD and related disorders.

Objective To understand the HIV-hepatitis B virus (HBV) epidemic from a global perspective by clinically and virologically characterizing these viruses at the time of antiretroviral therapy (ART) initiation in a multi-national cohort. Methods and design HIV-infected subjects enrolled in two international studies were classified as HIV-HBV co-infected or HIV monoinfected prior to ART. HIV-HBV co-infected subjects were tested for HBV characteristics, hepatitis D virus (HDV), a novel non-invasive marker of liver disease, and drug-resistant HBV. Comparisons between discrete covariates used chi-square or Fisher’s exact tests (and Jonchkheere-Terpstra for trend tests) while continuous covariates were compared using Wilcoxon Rank-Sum Test. Results Of the 2105 HIV-infected subjects from 11 countries, the median age was 34 years and 63% were Black. The 115 HIV-HBV co-infected subjects had significantly higher ALT and AST values, lower body mass index, and lower CD4+ T-cell counts than HIV monoinfected subjects (median 159 cells/mL and 137 cells/mL, respectively, P=0.04). In the co-infected subjects, 49.6% had HBeAg-negative HBV, 60.2% had genotype A HBV, and 13% were HDV positive. Of the HBeAg-negative subjects, 66% had HBV DNA ≤2000 IU/ml compared to 5.2% of the HBeAg-positive subjects. Drug-resistant HBV was not detected. Conclusions Screening for HBV in HIV-infected patients in resource-limited settings is important since it is associated with lower CD4+ T-cell counts. In settings where HBV DNA is not available, HBeAg may be useful to assess the need for HBV treatment. Screening for drug-resistant HBV is not needed prior to starting ART in settings where this study was conducted.