Which is most commonly mutated gene in Surfactant Dysfunction Disorders:
**Core Concept**
Surfactant Dysfunction Disorders, also known as Infant Respiratory Distress Syndrome (IRDS), are a group of conditions characterized by impaired lung function due to defects in surfactant production or function. Surfactant is a complex mixture of phospholipids and proteins that reduces surface tension in the lungs, facilitating easier lung expansion and gas exchange.
**Why the Correct Answer is Right**
The most common genetic cause of Surfactant Dysfunction Disorders is mutations in the surfactant protein B (SFTPB) gene. These mutations lead to decreased production or function of surfactant protein B, resulting in impaired surfactant function and abnormal lung development. The SFTPB gene is crucial for the normal production and function of surfactant protein B, and mutations in this gene account for approximately 20% of cases of Surfactant Dysfunction Disorders.
**Why Each Wrong Option is Incorrect**
**Option A:** Mutations in the surfactant protein A (SFTPA) gene have been associated with certain cases of Surfactant Dysfunction Disorders, but they are less common than SFTPB mutations.
**Option B:** The surfactant protein C (SFTPC) gene has been implicated in a subgroup of patients with Surfactant Dysfunction Disorders, particularly those with a history of pulmonary fibrosis. However, SFTPC mutations are not the most common cause of Surfactant Dysfunction Disorders.
**Option C:** The ABCA3 gene encodes a protein involved in the transport of surfactant lipids, and mutations in this gene have been associated with some cases of Surfactant Dysfunction Disorders. However, ABCA3 mutations are not the most common genetic cause of these disorders.
**Clinical Pearl / High-Yield Fact**
Surfactant Dysfunction Disorders are often associated with a history of prematurity, and mutations in the SFTPB gene may be more common in this population. Newborn screening programs have been developed to identify infants at risk of Surfactant Dysfunction Disorders, and early intervention with surfactant replacement therapy can significantly improve outcomes.
**Correct Answer:** C. ABCA3