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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Pulmonology · SFTPC-Related Interstitial Lung Disease

Understanding Interstitial Lung Disease Due to SP-C Deficiency

At a Glance

SFTPC-related interstitial lung disease is a rare genetic condition caused by inherited or new SFTPC changes that disrupt lung surfactant. Symptoms range from newborn breathing problems to later mild disease, so care is individualized with monitoring and support.

Learning that you or your child has a rare genetic condition can feel overwhelming, especially when the diagnosis—SFTPC-related interstitial lung disease—is one that many local doctors may not have encountered before. This condition, also known as surfactant protein C deficiency, affects the specialized cells in the lungs that produce surfactant, a substance that keeps the air sacs (alveoli) open so we can breathe [1][2].

Because this condition is so rare, there are no exact numbers on how many people are affected worldwide [3]. What we do know is that it varies significantly from person to person; some children are diagnosed as newborns, while others don’t show symptoms until later in childhood or even adulthood [4][5].

The Biological Mechanism: A Protein “Traffic Jam”

To understand this condition, it helps to look at the SFTPC gene. This gene provides the instructions for making pro-SP-C, a “parent” protein that is eventually cut and folded into the active surfactant protein C (SP-C).

When there is a mutation in the SFTPC gene, the body produces a misfolded or “broken” version of this protein [6]. Instead of being a simple lack of protein, the problem is often a toxic gain of function. This means the mutant protein doesn’t just fail to work; it becomes actively harmful [7]. While these mechanisms are well described for important variants, not every variant follows the exact same pathway.

  • Misfolding and Aggregation: The mutant protein cannot fold into the correct shape. These “sticky” misfolded proteins clump together (aggregate) inside the cell [6].
  • Endoplasmic Reticulum (ER) Stress: Proteins are normally folded in a part of the cell called the endoplasmic reticulum (ER). When it becomes clogged with misfolded proteins, it triggers a “stress response” [8].
  • Cell Injury: Over time, this stress can injure or kill alveolar type II cells. These cells are the “engine room” of the lung’s air sacs, responsible for both making surfactant and repairing the lungs after injury [9][10].
  • Inflammation and Scarring: As these cells are damaged, the body tries to heal, which can lead to chronic inflammation (alveolitis) and eventually permanent scarring (fibrosis) [11][12]. Note that fibrosis is a possible outcome, not an inevitable result for everyone.

Inherited vs. Spontaneous Mutations

You may wonder how this happened, especially if there is no history of lung disease in your family. There are two ways an SFTPC mutation occurs:

  1. Inherited: The mutation is passed down from a parent. This follows an autosomal dominant pattern, meaning a child only needs to inherit one copy of the mutated gene to be at risk [13]. A parent with a disease-causing variant has a 1-in-2 chance of passing it to each child.
  2. De Novo (Spontaneous): The mutation occurs for the first time in the child, with neither parent carrying the gene [14].

It is important to know that this gene has variable penetrance. This means that even if a parent carries the mutation, they might have very mild symptoms or no symptoms at all, while their child may be more severely affected [13][15]. A genetic counselor can help explain testing of relatives and reproductive options.

A Wide Range of Outcomes

One of the most challenging aspects of SP-C deficiency is its unpredictability. Even people with the exact same mutation can have very different experiences [15].

  • Infancy: Some babies experience severe respiratory distress shortly after birth [1].
  • Childhood: Others may develop a chronic cough, fast breathing, or a need for supplemental oxygen during early childhood [16].
  • Stability and Change: Some children remain stable or even improve for many years, while others may experience a gradual worsening of lung function [17].

Managing a Rare Diagnosis

Because this condition is rare, care is typically managed by a specialized team at an interstitial lung disease center. Management focuses on supporting the lungs and monitoring for complications:

  • Oxygen Support: For those who need it, supplemental oxygen supports adequate blood oxygen levels, which are important for normal organ function and development [14].
  • Monitoring Growth: Because breathing takes so much energy, extra nutritional support is often needed to help children gain weight [2].
  • Screening for Complications: Doctors will watch for pulmonary hypertension (high blood pressure in the lung arteries), which can happen if lung disease is severe [18][19].
  • Trialing Medications: While there is no “cure” for the genetic mutation itself, doctors sometimes try medications like hydroxychloroquine or steroids to reduce lung inflammation, though their effectiveness varies greatly between patients [20][14].

In cases of progressive respiratory failure that does not respond to other treatments, a lung transplant may eventually be considered [2][21]. Identifying the mutation early allows your medical team to tailor a monitoring plan specifically for your needs [2].

Common questions in this guide

What exactly is SFTPC-related interstitial lung disease?
SFTPC-related interstitial lung disease is a rare genetic lung condition caused by a change in the SFTPC gene. The change can create an abnormal surfactant protein that injures lung cells and may cause inflammation or scarring; symptoms can begin in infancy, childhood, or adulthood.
Can SP-C deficiency be passed from a parent to a child?
Yes. If a parent carries a disease-causing SFTPC variant, each child has a 1-in-2 chance of inheriting it. The change can also arise for the first time in a child, and a parent who carries it may have few or no symptoms.
What symptoms might someone with SP-C deficiency develop?
Symptoms may include severe breathing problems soon after birth, chronic cough, fast breathing, reduced activity, or a need for supplemental oxygen. Some people remain stable or improve, while others gradually lose lung function.
How is SFTPC-related lung disease treated?
Care focuses on supporting breathing and monitoring for complications. Supplemental oxygen and extra nutrition may be needed; doctors may try hydroxychloroquine or steroids for lung inflammation, although responses vary. Lung transplantation may be considered when respiratory failure progresses despite other treatment.
Why are people with SP-C deficiency screened for pulmonary hypertension?
Pulmonary hypertension is high blood pressure in the arteries of the lungs and can develop when lung disease is severe. The care team may screen for it regularly, with the timing based on the person's symptoms, lung status, and test results.
Should healthy parents or siblings have genetic testing?
Parents and siblings may benefit from genetic counseling and testing even if they have no breathing symptoms, because SFTPC variants can have different effects within the same family. A genetic counselor can review the exact variant, discuss who should be tested, and explain reproductive options.
When might a lung transplant be considered?
A transplant evaluation may be considered when lung disease causes progressive respiratory failure and does not respond adequately to other treatments. The interstitial lung disease and transplant teams can discuss timing based on lung function and response to treatment.

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References

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This page is for informational purposes only and does not constitute medical advice about SFTPC-related interstitial lung disease. Your pulmonologist, genetic counselor, and specialized interstitial lung disease team can interpret genetic results and recommend monitoring or treatment for your situation.

Guide contents Interstitial lung disease due to SP-C deficiency
Research & Literature
02 Recognizing the Signs