The neonatal feature of cystic fibrosis is
**Core Concept**
Cystic fibrosis is a genetic disorder that primarily affects the respiratory, digestive, and reproductive systems. The neonatal feature of cystic fibrosis is related to the abnormal production of sweat, which is used as a diagnostic tool to detect the disease.
**Why the Correct Answer is Right**
The neonatal feature of cystic fibrosis is the presence of a salty taste in the newborn's skin, indicating abnormal sweat gland function. This is due to mutations in the CFTR gene, which encodes for a chloride channel. Normally, chloride ions are secreted into the sweat, but in cystic fibrosis, the mutated chloride channel leads to abnormal sweat composition, resulting in a salty taste. This salty taste is a characteristic feature of cystic fibrosis in newborns.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not relate to the neonatal feature of cystic fibrosis. While meconium ileus is a gastrointestinal complication of cystic fibrosis, it is not a neonatal feature.
**Option B:** This option is incorrect as it is a complication of cystic fibrosis, but not a neonatal feature. Pneumonia is a common respiratory complication of cystic fibrosis, but it is not a characteristic feature of the disease in newborns.
**Option C:** This option is incorrect as it is not a specific feature of cystic fibrosis. Failure to thrive can be a result of many conditions, including cystic fibrosis, but it is not a unique characteristic of the disease in newborns.
**Clinical Pearl / High-Yield Fact**
The salty taste in the newborn's skin is a classic sign of cystic fibrosis, and it is essential to diagnose the disease early to prevent complications.
**Correct Answer:** D