Presenilin – 1 gene is present on :
**Core Concept**
The **presenilin-1 (PSEN1) gene** is a key component in the pathogenesis of Alzheimer's disease, particularly in familial forms. It encodes for a protein that is involved in the **gamma-secretase complex**, which is crucial for the processing of amyloid precursor protein. The location of this gene is critical for understanding genetic factors in neurodegenerative diseases.
**Why the Correct Answer is Right**
The **PSEN1 gene** is indeed located on chromosome 14. This gene's mutation can lead to early-onset familial Alzheimer's disease by affecting the **amyloid beta peptide** production through the gamma-secretase complex. Understanding the genetic basis, including the location of such genes, is vital for diagnosing and potentially treating these conditions.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because the PSEN1 gene is not located here.
**Option B:** Similarly, this option is also incorrect as it does not correspond to the location of the PSEN1 gene.
**Option D:** This option is incorrect as well; the correct location is not on this chromosome.
**Clinical Pearl / High-Yield Fact**
Remembering that **chromosome 14** is associated with the **PSEN1 gene** is crucial for exams, as it links to familial Alzheimer's disease. This knowledge can help in distinguishing between different forms of dementia and in understanding the genetic counseling aspects.
**Correct Answer:** D. Chromosome 14