UK study reports ciHHV-6 not associated with classical Hodgkin’s lymphoma
While recent studies have suggested HHV-6 is associated with classical Hodgkin’s lymphoma (cHL), results from the largest study, to date, to investigate the prevalence of ciHHV-6 among cHL patients and controls in Scotland, demonstrate that inheritance of ciHHV-6 does not increase the risk of developing this disease. CiHHV-6 was detected and confirmed via ddPCR in 10/563 (1.8%) of controls from the UK, compared to 16/936 (1.7%) of cHL patients. These findings are in line with prevalence data found among some patient populations (2%), but are somewhat higher than the range previously reported for US and UK control populations (0.8-0.85%) (Pellett 2011).
The Scottish group, led by Ruth Jarrett and Adam Bell at the University of Glasgow, also found that ciHHV-6A is less prominent than in other regions, such as Sub-Saharan Africa (Bates 2009) where the percentage of HHV-6A cases accounts for approximately one-third of all detected HHV-6 species. This confirms that there are likely significant differences in ciHHV-6 prevalence according to region. For example, the prevalence in Japan has been consistently shown to be much lower than in other populations, at approximately 0.2% (Ablashi 2014).
The authors also found ciHHV-6 more often in older adults (2.97%) than in younger adults (1.03%). In addition, they identified an individual with four integrated copies of HHV-6A per cell. Case reports have previously described individuals with two copies of integrated virus (with one integrated genome inherited from each parent). In this case, the authors were not certain if this individual inherited two integrated copies from each parent, and offer several alternative explanations for this phenomenon, which include: (1) a new primary integration event, (2) reactivation and further integration of an inherited virus, or (3) integration of viral genome concatemers.