KRAS and pachyonychia congenita: In recent years, liquid biopsy has also focused on DNA extraction from the urine of PC patients, with the hypothesis based on cfDNA originating from the shedding of cells from the genitourinary tract or through the kidney and the glomerulus: analysis of KRAS mutations with droplet digital PCR showed heterogeneous results according to renal functions, with a detection rate of urine KRAS mutations increasing in the group with a worse creatinine clearance rate [183].