In the Knudson two-hit hypothesis applied to retinoblastoma, the hereditary form differs from the sporadic form in that:
- A The first hit is a somatic mutation in both forms
- B In hereditary form, the first hit is a germline mutation present in all cells ✓
- C Only one hit is required in the hereditary form
- D Sporadic form is bilateral and multifocal
Correct answer: B. In hereditary form, the first hit is a germline mutation present in all cells
Explanation
In hereditary retinoblastoma, the first RB1 mutation is germline, present in all somatic cells; only one additional somatic hit is needed for tumor formation, making bilateral/multifocal disease common. Sporadic retinoblastoma requires both hits to occur somatically in the same cell, so it is unilateral and unifocal. Two hits are required in both forms.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.