Characterisation of germline gene variants, including copy number variation, in the SMAD4, BMPR1A, STK11 and GREM1 genes, requested by a specialist or consultant physician, for a patient: (a) who has non-adenomatous polyposis; and (b) who is assessed by the specialist or consultant physician as being at a risk of more than 10% of having any of the following, on the basis of clinical and family history criteria: (i) juvenile polyposis syndrome; (ii) Peutz-Jeghers syndrome; (iii) hereditary mixed polyposis syndrome