Treatment Strategy: Lungs, Electrolytes, and Nutrition

Because BESC1 is a rare genetic condition caused by CA12 deficiency, there is currently no cure. Instead, the standard of management focuses on controlling the symptoms—primarily protecting the lungs and keeping the body’s fluid and electrolyte levels balanced ^[1][2].

Treatment is highly personalized and largely extrapolated from the management of non-CF bronchiectasis and pediatric electrolyte disorders, rather than relying on BESC1-specific clinical trials. Your care team will likely include a pulmonologist (lung specialist) and a metabolic or endocrine specialist to help manage salt loss.

Maintaining Salt and Fluid Balance

The most immediate goal, especially for infants and young children, is to prevent hyponatremia (dangerously low sodium). Because the body “wastes” salt through sweat, patients need to carefully manage their salt intake ^[3][4].

• Prescribed Oral Salt Supplementation: Many patients require an individualized, prescribed oral sodium replacement regimen to replace what they lose in sweat. The specific formulation, concentration, and dose of salt must be carefully prescribed by a specialist based on weight, laboratory results, and kidney function ^[3]. Never improvise concentrated salt solutions or salt tablets without a doctor’s direction, as inappropriate replacement can cause severe sodium or volume imbalances.
• Heat and Exercise Safety: In adolescents and older children, the risk shifts toward physical activity. In hot weather or during sports, individuals with BESC1 must follow a clinician-approved hydration plan to prevent muscle breakdown (rhabdomyolysis) and severe dehydration ^[4].
• Emergency / Sick-Day Plan: If a fever or a stomach bug (vomiting/diarrhea) occurs, salt can be lost much faster than normal. You must have a clear, written “sick-day plan” from your clinician detailing exactly how to adjust fluids and electrolytes, and at what point to seek emergency care ^[3].

Protecting the Lungs

Even though the cause is different, the lung damage in BESC1 can look very similar to Cystic Fibrosis. The goal is to keep the airways clear and treat exacerbations early before they cause permanent scarring (bronchiectasis) ^[5][2].

• Airway Clearance Therapy (ACT): These are techniques used to help move mucus out of the lungs. A respiratory therapist will typically help select an individualized technique. This might include manual chest physical therapy, specialized breathing exercises, or using a “vest” or oscillating “PEP” device ^[1]. Any inhaled therapies (like hypertonic saline) should only be used if prescribed, as they may require tolerance testing.
• Managing Exacerbations: A new or worsening cough does not automatically mean antibiotics are required. Your doctor will evaluate respiratory changes to determine if they represent a clinically meaningful “pulmonary exacerbation.” Treatment is often guided by sputum cultures (testing mucus for bacteria) to identify the specific bacteria present ^[5][1].
• Preventative Care: Routine vaccinations (like influenza and pneumococcal vaccines), avoiding secondhand smoke, and good infection control practices are critical for preserving lung health over time.

Nutrition and Growth

Salt loss often makes it difficult for infants to gain weight, leading to “failure to thrive” ^[2].

• Dietitian-Led Support: Nutrition support is based on the individual’s specific growth trajectory and intake. Some patients may require a higher-calorie diet to ensure they have enough energy to grow while the body works harder to maintain its salt balance ^[3].
• Pancreatic Considerations: While the CA XII enzyme is present in various tissues, pancreatic insufficiency is not established as a routine, universal feature of BESC1. Pancreatic testing and the use of digestive enzymes should only be considered if clinical symptoms warrant specialist evaluation ^[6][2].

Why CFTR Modulators Won’t Work

You may have heard of “breakthrough” drugs for Cystic Fibrosis called CFTR modulators (such as Trikafta, Kalydeco, or Symdeko). These drugs are not indicated or expected to work for CA12 deficiency ^[1].

CFTR modulators are designed to correct the CFTR protein. Because the primary molecular cause of BESC1 is the CA XII enzyme, taking a CFTR modulator for BESC1 alone would not address the actual source of the problem ^[2][1]. Unless a specialist identifies a separate, coexisting CFTR-related indication, your team will focus on the salt and lung treatments that directly address the CA12 deficiency.