A newborn male develops intracranial hemorrhage after a circumcision. PT is markedly prolonged, aPTT is normal, platelet count and bleeding time are normal. Factor assay shows isolated Factor VII deficiency. The most likely inheritance pattern is:

• A Autosomal recessive ✓
• B X-linked recessive
• C Autosomal dominant with variable penetrance
• D Mitochondrial inheritance

Explanation

Factor VII (FVII) deficiency is a rare autosomal recessive disorder caused by mutations in the F7 gene (chromosome 13q34). Isolated Factor VII deficiency uniquely prolongs the PT (extrinsic pathway) without affecting the aPTT (intrinsic/common pathway) since Factor VII participates ONLY in the extrinsic pathway (tissue factor-VIIa complex). This pattern — prolonged PT with normal aPTT — distinguishes it from hemophilias (which prolong aPTT only) and common pathway factor deficiencies (which prolong both). Treatment: recombinant FVIIa. Von Willebrand disease affects bleeding time/ristocetin; hemophilia A (FVIII) and B (FIX) are X-linked.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.