Additionally, a higher-than-expected number of breast cancer cases were identified in women with NF1 who were younger than 50 years of age, giving a five-fold increased risk of breast cancer in this age group compared to women younger than 50 years old in the general population (SIR = 5.08; 95%CI 3.77–6.81). This evidence concerns the gene NF1 and breast carcinoma.