NHLH1 and myalgic encephalomeyelitis/chronic fatigue syndrome: The presence of B19V specific NS1 antibodies indicates a severe and persistent or chronic B19V infection; in this study, 73% of those with anti-NS1 antibodies suffered from joint pain, and positivity for these antibodies in ME/CFS patients was associated with greater expression of the human ME/CFS-associated genes NHLH1 and GABPA [116].