Finding Answers: Genetic Testing and Diagnostic Procedures

When a baby’s lungs aren’t working as expected, doctors use a “staged evaluation.” This involves a series of tests to build a complete picture of your baby’s lung health ^[1]. Recent 2025 guidelines from the American Thoracic Society (ATS) emphasize obtaining genetic answers early for infants with suspected surfactant dysfunction ^[2].

The Priority of Rapid Genetic Testing

The 2025 ATS guidelines strongly recommend rapid, broad genetic testing as a primary diagnostic tool for infants presenting with Childhood Interstitial Lung Disease (chILD) and respiratory failure ^[2].

• Why Genetic Testing?: It requires only a blood or saliva sample and can identify specific variants in genes like SFTPB, SFTPC, ABCA3, or NKX2-1 ^[3].
• Rapid Protocols: For critically ill babies in the NICU, “rapid” sequencing can often return results in days rather than weeks ^[2].
• Not a Replacement: While genetic testing is prioritized, it does not replace the need to evaluate for infections, congenital heart disease, or aspiration ^[2].

Understanding Your Genetic Report

Genetic testing does not always provide a simple “yes or no” answer ^[4]:

• Pathogenic / Likely Pathogenic: The test found a variant known to cause disease.
• Negative Result: No known disease-causing variants were found. A negative result does not completely rule out a genetic cause, as current tests cannot detect every possible DNA change.
• Variant of Uncertain Significance (VUS): A change was found, but there is not enough medical evidence to know if it causes disease. A VUS should not be used by itself to diagnose or direct treatment.
• Reanalysis: As scientific knowledge grows, tests can sometimes be re-analyzed months or years later to see if a VUS has been reclassified.

Imaging the Lungs and Heart

While genetic tests are being processed, your team will use imaging to see how the lung tissue is changing ^[1].

High-Resolution Chest CT (HRCT)

An HRCT provides a detailed picture of the lungs. Doctors look for specific patterns, such as “ground-glass opacities” or “septal thickening” ^[5][6]. While helpful, these findings are not specific only to surfactant dysfunction; they can also be seen with infections, fluid buildup, or other lung diseases ^[5].

Echocardiogram

Because lung disease puts extra pressure on the heart, a specialized ultrasound of the heart (echocardiogram) is essential ^[1]. It screens for pulmonary hypertension (high blood pressure in the lung’s arteries). Echocardiography estimates this pressure and helps doctors monitor heart strain over time ^[7].

The Role of Bronchoscopy

A bronchoscopy involves placing a small camera into the baby’s airways ^[8]. Doctors may perform a Bronchoalveolar Lavage (BAL), rinsing a small area of the lung with salt water to collect fluid ^[9].

• What it tells us: It can help evaluate for infections, bleeding, or show if certain surfactant proteins are missing ^[9][10].
• What it doesn’t tell us: BAL cannot completely “rule out” all infections, and it cannot provide a definitive genetic diagnosis ^[2].

When Is a Surgical Lung Biopsy Necessary?

A surgical lung biopsy involves taking a small piece of lung tissue for examination under a microscope ^[11]. It is an invasive surgery with significant risks, especially for small, medically complex infants ^[12][13].

Under the 2025 ATS guidelines, surgical biopsy is strongly recommended only in specific situations ^[2]:

1. Urgency: When a specific diagnosis is urgently needed and genetic testing is infeasible, delayed, or inconclusive ^[2].
2. Treatable Traits: When doctors believe the biopsy will identify specific patterns of inflammation or scarring that will directly change the medication or treatment plan ^[2].
3. Prognosis: When a clearer understanding of the disease is needed to make difficult care decisions ^[2].

Your medical team will carefully weigh the risks of biopsy against the likelihood that the results will actually change your baby’s medical management ^[2].