Of the remaining 27 children, eight unvaccinated children had high IgG antibody levels but were sampled too late to be IgM positive and no adequate sample was collected from 19 children, mainly because the child had died, was admitted to hospital, had travelled, or was seen only after the measles vaccination at age 9 months when it would be impossible to assess whether antibodies were due to measles infection or to vaccination. The gene discussed is CD40LG; the disease is measles.