**Core Concept**
MODY (Maturity-Onset Diabetes of the Young) is a form of diabetes mellitus caused by mutations in genes that regulate insulin production in the pancreas. These mutations lead to impaired insulin secretion, resulting in hyperglycemia.

**Why the Correct Answer is Right**
MODY is a rare form of diabetes, accounting for approximately 1-2% of all diabetes cases. It typically presents in young adulthood and is characterized by a strong family history of diabetes. The mutations responsible for MODY affect genes that encode transcription factors, such as HNF1A, HNF4A, and HNF1B, which regulate the expression of insulin and other genes involved in glucose metabolism. The impaired insulin secretion in MODY is due to the reduced expression of insulin and other pancreatic hormones.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because MODY is not caused by insulin resistance, which is a hallmark of type 2 diabetes. MODY is characterized by impaired insulin secretion, not insulin resistance.

**Option B:** This option is incorrect because MODY is not caused by autoimmune destruction of pancreatic beta cells, which is a feature of type 1 diabetes. MODY is caused by genetic mutations that impair insulin production.

**Option C:** This option is incorrect because MODY is not caused by pancreatic exocrine dysfunction, which is a feature of cystic fibrosis and other conditions. MODY is a form of diabetes that affects insulin production.

**Clinical Pearl / High-Yield Fact**
MODY is often misdiagnosed as type 1 or type 2 diabetes due to its similar presentation. However, MODY typically presents in young adulthood and has a strong family history of diabetes, distinguishing it from other forms of diabetes.

**Correct Answer: D. MODY is caused by mutations in genes that regulate insulin production in the pancreas.**