Question

The gene that regulates normal morphogenesis during development is

• A. FMR-1 gene
• B. Homeobox gene
• C. P-16
• D. PTEN

Hint:

Homeobox (Hox) genes are the master transcription factor genes that set up the body's anteroposterior pattern during development.

Answer 1

The Correct Option is B

Step 1: Understanding the Question.
We need the gene family whose normal job is to control body shape and organ patterning as the embryo develops, that is, morphogenesis.

Step 2: Key Concept.
Homeobox genes, also called Hox genes, code for transcription factors that switch on the right combination of downstream genes in the right body segment at the right time. They set up the head to tail (anteroposterior) body plan and guide limb and organ patterning, so they directly regulate normal morphogenesis.

Step 3: Detailed Explanation.
FMR-1 is the familial mental retardation gene. Its abnormal expansion causes fragile X syndrome, which affects neuronal function and intellectual development, not general body patterning.
P-16 (CDKN2A) is a tumor suppressor gene that slows the cell cycle by inhibiting cyclin dependent kinases, protecting against cancer, not a morphogenesis regulator.
PTEN is also a tumor suppressor, a phosphatase that opposes the PI3K-AKT growth pathway, and its loss is linked with cancers of the breast, prostate and other organs, again a growth control gene rather than a body-plan gene.
Only homeobox genes are the master regulators of segmental body patterning during embryogenesis, and mutations in them classically cause patterning defects such as syndactyly or polydactyly.

Step 4: Final Answer.
The gene regulating normal morphogenesis during development is the homeobox gene, option (2).