Loss of heterozygosity or intragenic mutation, which comes first?

@article{Wilentz2001LossOH,
  title={Loss of heterozygosity or intragenic mutation, which comes first?},
  author={Robb E. Wilentz and Pedram Argani and Ralph H. Hruban},
  journal={The American journal of pathology},
  year={2001},
  volume={158 5},
  pages={1561-3}
}