A 25-year-old woman has a molar pregnancy. Karyotype is 46,XX. Genetic analysis shows all chromosomes are of paternal origin. What is the mechanism?

• A Fertilization of an empty ovum by two different sperm
• B Fertilization of a normal ovum by two sperm
• C Fertilization of an empty ovum by a single sperm that duplicates ✓
• D Fertilization of a normal ovum by a single sperm that duplicates

Explanation

C complete hydatidiform mole is typically 46,XX with all chromosomes of paternal origin. This occurs when a single sperm fertilizes an empty ovum lacking maternal DNA and duplicates its own DNA. Fertilization of a normal ovum by two sperm results in a partial mole, which is triploid. Fertilization of an empty ovum by two different sperm also yields a complete mole but is not from duplication of a single sperm.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.