<prompt> A 9 year old boy with elevation in both PT and A PTT. What is the diagnosis? -Defect in extrinsic pathwayDefect in intrinsic pathwayPlatelet function defectDefect in common pathway  <response>: APTT is used to measure the intrinsic system factors as well as factors common to both intrinsic and extrinsic system. PT measures extrinsic system factor as well as factors in common pathway. As both are affected defect is in common pathway. Reference : Harsh Mohan textbook of pathology, 7th edition.Pg no.307,308 