Efficient identification of somatic mutations in acute myeloid leukaemia using whole exome sequencing of fingernail derived DNA as germline control

Recent advances in next-generation sequencing have made it possible to perform genome wide identification of somatic mutation in cancers. Most studies focus on identifying somatic mutations in the protein coding portion of the genome using whole exome sequencing (WES). Every human genome has around 4 million single nucleotide polymorphisms (SNPs). A sizeable fraction of these germline SNPs is very rare and will not be found in the databases. Thus, in order to unambiguously identify somatic mutation, it is absolutely necessary to know the germline SNPs of the patient. While a blood sample can serve as source of germline DNA from patients with solid tumours, obtaining germline DNA from patients with haematological malignancies is very difficult. Tumor cells often infiltrate the skin, and their DNA can be found in saliva and buccal swab samples. The DNA in the tips of nails stems from keratinocytes that have undergone keratinization several months ago. DNA was successfully extracted from nail clippings of 5 probands for WES. We were able to identify somatic mutations in one tumor exome by using the nail exome as germline reference. Our results demonstrate that nail DNA is a reliable source of germline DNA in the setting of hematological malignancies.