The US study showed that the chance of developing radiation-induced breast cancer may outweigh the benefits of mammograms for women under 30 with the BRCA1 or BRCA2 genes.
Although women in the UK usually start breast screening on the NHS between the ages of 50 and 70, many younger women carrying the gene are advised to undergo mammograms earlier.
Researchers said it is not clear whether the risk of radiation-induced breast cancer would limit the benefit of early mammography.
They found that women who underwent five mammograms between the ages of 24 and 29 would have an additional 26 breast cancers per 10,000 women than other age groups.
Amy Berrington de Gonzalez, of the Johns Hopkins Bloomberg School of Public Health in Baltimore, concluded: "In the absence of direct empirical data, our estimates can be used by those involved in the decision-making process for BRCA mutation carriers to assess whether the benefits from early mammographic screening are likely to outweigh the radiation risks."