In children with poor asthma control more frequently than in children with sufficiently controlled asthma (66% versus 55% of children) a deficiency of one or more IgG subclasses and IgG3 or IgG4 deficiency were diagnosed as well as solely in this group of children, a combined IgA and IgG subclass deficiency was revealed. This evidence concerns the gene IGHG3 and asthma.