ADSS2 and childhood onset asthma: When searching for PoO effects in childhood asthma across the whole genome, we found that the effect alleles at two SNPs, rs3003214 and rs3003211, near the gene for adenylosuccinate synthase 2 (ADSS2 on chromosome 1q44) were significantly associated with childhood asthma in opposite directions depending on the parental origin of the alleles.