Which of the following disorder is classified under defects in metabolic pathways?
**Core Concept**
Metabolic disorders refer to a group of conditions arising from defects in metabolic pathways, which are crucial for energy production, growth, and maintenance of cellular homeostasis. These disorders can be inherited or acquired, and they often result in the accumulation of toxic substances or the deficiency of essential nutrients.
**Why the Correct Answer is Right**
Disorders classified under defects in metabolic pathways include those affecting the breakdown and synthesis of carbohydrates, fats, and proteins. One example is **Galactosemia**, a genetic disorder caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase. This enzyme is essential for the metabolism of galactose, a sugar found in milk and dairy products. When this enzyme is deficient, galactose accumulates in the body, leading to various complications, including cataracts, liver dysfunction, and developmental delays. Other disorders classified under defects in metabolic pathways include **Phenylketonuria (PKU)**, **Tyrosinemia**, and **Maple Syrup Urine Disease**.
**Why Each Wrong Option is Incorrect**
* **Option A:** Disorders classified under defects in metabolic pathways do not typically include those caused by defects in the immune system, such as **Immunodeficiency disorders**.
* **Option B:** Although **Genetic disorders** can be classified under defects in metabolic pathways, not all genetic disorders are metabolic in nature.
* **Option D:** **Infectious diseases** are not classified under defects in metabolic pathways, as they are caused by external pathogens rather than defects in cellular metabolism.
**Clinical Pearl / High-Yield Fact**
A key aspect of managing metabolic disorders is identifying the underlying enzyme deficiency and implementing a specific diet or treatment plan to prevent the accumulation of toxic substances.
**Correct Answer:** C.