A subsequent study by Roth et al (2000) did not find any significant effect of CYP1A1 exon 7 polymorphisms in 56 individuals with mild or moderate squamous dysplasia and 56 control individuals (a relatively small sample size) from Linxian, a region of high oesophageal cancer risk in China. The gene discussed is CYP1A1; the disease is carcinoma of esophagus.