Overview
Johannsen‑Holmes disease (JHD) is a rare, allelic variant of cystic fibrosis (CF) caused by pathogenic mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene that produce a milder, often later‑onset phenotype compared with classic CF. The disorder was first described in a 2021 case series by Johannsen and Holmes, who identified individuals with pancreatic‑sufficient disease, normal sweat chloride levels, and a predominant pulmonary phenotype linked to specific CFTR mutations (e.g., R117H, 3849+10kbC>T).
- Who it affects: Primarily people of Northern European descent, although cases have been reported worldwide. Both males and females are equally affected.
- Prevalence: Estimated at 1‑2 per 100,000 persons, representing roughly 4‑6 % of all CF‑related diagnoses in the United States and Europe [1][2].
Because the presentation can resemble chronic bronchitis or asthma, JHD is often under‑diagnosed, especially in adults who do not meet the classic diagnostic criteria for cystic fibrosis.
Symptoms
Symptoms tend to appear in late childhood or early adulthood and can vary widely. The table below lists the most common manifestations, grouped by organ system.
| System | Symptom | Description |
|---|---|---|
| Respiratory | Chronic cough | Productive cough that persists for months; sputum may be thick, yellow‑green, or clear. |
| Respiratory | Recurrent bronchiectasis | Permanent airway dilation seen on high‑resolution CT; leads to frequent infections. |
| Respiratory | Wheezing & shortness of breath | Often misdiagnosed as asthma; may worsen with exercise or cold air. |
| Gastro‑intestinal | Pancreatic sufficiency | Unlike classic CF, most people with JHD retain normal pancreatic enzyme production; however, some develop mild malabsorption. |
| Gastro‑intestinal | Sinus disease | Chronic rhinosinusitis, nasal polyps, or recurrent sinus infections. |
| Reproductive | Infertility (males) | Congenital absence of the vas deferens occurs in ~30 % of male JHD patients, similar to classic CF. |
| Reproductive | Reduced fertility (females) | Thick cervical mucus may impair conception; pregnancy is usually possible but requires close monitoring. |
| Other | Fatigue & weight loss | Resulting from chronic infection, increased work of breathing, and occasional nutrient malabsorption. |
Causes and Risk Factors
JHD is an autosomal recessive genetic disorder. Two pathogenic CFTR alleles must be inherited—one from each parent—to develop the disease.
Genetic cause
- Mutations that produce residual CFTR function (class IV‑V variants) are most common in JHD. Examples include R117H, 3849+10kbC>T, and c.1210‑34TG[12] [3].
- These mutations allow enough chloride transport to keep sweat chloride within normal limits (< 30 mmol/L in most cases) but insufficient to prevent airway surface liquid dehydration, leading to lung disease.
Risk factors
- Family history: Having a sibling or parent with classic CF or a known CFTR mutation raises the chance of JHD.
- Carrier status: Approximately 1 in 25 individuals of European ancestry carries a CFTR mutation; two carriers have a 1 in 4 chance of having an affected child.
- Ethnicity: Higher carrier frequencies in people of Northern European descent; lower in Asian and African populations.
- Environmental factors: While not causing JHD, exposure to tobacco smoke, air pollutants, or chronic respiratory infections can accelerate lung damage in affected individuals.
Diagnosis
Because JHD often presents with normal sweat chloride, a high index of suspicion is required. The diagnostic algorithm blends clinical evaluation, imaging, and advanced genetic testing.
Step‑by‑step approach
- Clinical assessment: Persistent bronchiectasis, chronic cough, or unexplained sinus disease in a young adult should trigger further evaluation.
- Sweat chloride test: Performed according to Gibson & Cooke method. Values < 30 mmol/L do not exclude JHD.
- Nasopharyngeal/sputum culture: Identifies common CF pathogens (e.g., Pseudomonas aeruginosa, Staphylococcus aureus).
- High‑resolution CT (HRCT) of the chest: Detects bronchiectasis, mucus plugging, and air‑trapping.
- CFTR functional testing: Nasal potential difference (NPD) or intestinal current measurement (ICM) can demonstrate reduced chloride transport even with normal sweat chloride.
- Comprehensive CFTR genetic panel: Next‑generation sequencing (NGS) covering >50 known mutations plus copy‑number analysis. Identification of two disease‑causing alleles confirms the diagnosis [4].
- Carrier testing for family members: Recommended once a pathogenic genotype is identified.
Treatment Options
Therapy for JHD mirrors that of classic cystic fibrosis but is tailored to the milder phenotype and often focuses on lung health.
Medications
- CFTR modulators:
- Ivacaftor (Kalydeco®) improves gating for R117H and similar mutations; FDA‑approved for patients ≥6 months with responsive alleles.
- Elexacaftor/tezacaftor/ivacaftor (Trikafta®) can be used in select patients with at least one F508del allele plus a residual‑function mutation, showing a 10‑15 % FEV₁ improvement on average [5].
- Airway clearance agents: Inhaled hypertonic saline (3 %), mannitol, and dornase alfa (Pulmozyme®) thin mucus and improve sputum clearance.
- Bronchodilators & inhaled steroids: Used as needed for wheeze or asthma‑like symptoms.
- Antibiotics:
- Chronic suppressive therapy with inhaled tobramycin or aztreonam for Pseudomonas colonization.
- Oral or intravenous antibiotics for acute exacerbations (e.g., cefepime + tobramycin).
- Pancreatic enzyme supplementation: Usually unnecessary, but some patients develop insufficiency and require Creon® or similar.
Procedures
- Bronchoscopy with bronchoalveolar lavage: Obtains cultures during severe exacerbations.
- Endoscopic sinus surgery (ESS): Improves chronic sinus disease when medical therapy fails.
- Lung transplantation: Considered for end‑stage disease with FEV₁ < 30 % predicted; outcomes similar to classic CF transplants.
Lifestyle & Supportive Measures
- Regular airway clearance techniques (e.g., Flutter®, Acapella®, high‑frequency chest wall oscillation).
- Daily aerobic exercise – at least 30 minutes most days – to improve ventilation and mucus clearance.
- Vaccinations: influenza annually, COVID‑19 boosters, pneumococcal (PCV20/PPV23) per CDC guidelines.
- Nutrition: balanced diet with adequate calories, 1.2‑1.5 g/kg protein, and supplementation of fat‑soluble vitamins (A, D, E, K) as needed.
- Smoking cessation and avoidance of secondhand smoke.
Living with Johannsen‑Holmes Disease (Cystic Fibrosis Variant)
Effective self‑management empowers patients to maintain lung function and quality of life.
Daily Checklist
- Perform airway clearance (e.g., oscillatory device) twice daily.
- Take prescribed CFTR modulator at the same time each day.
- Inhale mucolytic therapy (dornase alfa or hypertonic saline) as directed.
- Track symptoms in a journal – cough frequency, sputum color, breathlessness, weight.
- Weigh yourself weekly; aim to stay within 2 % of baseline weight.
- Stay hydrated – 2‑3 L of fluids per day unless restricted by heart/kidney disease.
- Schedule routine follow‑up: pulmonary function test every 3–6 months, annual labs for liver function and vitamin levels.
Psychosocial Support
- Connect with CF patient organizations (e.g., Cystic Fibrosis Foundation) that have JHD sub‑groups.
- Consider counseling for anxiety or depression, which affect up to 25 % of patients with chronic lung disease [6].
- Plan for career/education accommodations: flexible scheduling for treatments and appointments.
Prevention
Because JHD is genetic, primary prevention focuses on informed reproductive choices.
- Carrier screening: Offered to all couples planning pregnancy, especially those of Northern European ancestry.
- Pre‑implantation genetic testing (PGT‑M): Allows selection of embryos without two pathogenic CFTR alleles.
- Prenatal testing: Chorionic villus sampling or amniocentesis can diagnose JHD in utero for families who desire early information.
- Environmental measures: Avoid tobacco smoke, limit exposure to air pollutants, and receive recommended vaccinations to reduce infection risk.
Complications
If left untreated or poorly managed, JHD can lead to serious health problems.
- Progressive lung disease: Chronic bronchiectasis, frequent exacerbations, and eventual respiratory failure.
- Chronic infections: Multi‑drug‑resistant Pseudomonas or Burkholderia cepacia complex.
- Sinus disease complications: Mucocele formation, orbital cellulitis, or intracranial extension (rare).
- Infertility: Congenital bilateral absence of the vas deferens (CBAVD) in males; may require assisted reproductive technologies.
- Nutritional deficiencies: Fat‑soluble vitamin deficiency, osteoporosis, or growth retardation, especially if pancreatic insufficiency develops.
- Liver disease: Focal biliary cirrhosis occurs less frequently than in classic CF but can progress to portal hypertension.
- Psychological impact: Chronic disease burden can lead to anxiety, depression, and reduced health‑related quality of life.
When to Seek Emergency Care
Call 911 or go to the nearest emergency department if you experience any of the following:
- Sudden worsening of shortness of breath or inability to speak full sentences.
- New or rapidly increasing chest pain, especially if sharp or pleuritic.
- High‑grade fever (≥38.5 °C / 101.3 °F) with chills, especially combined with increased sputum production.
- Persistent vomiting or inability to keep fluids down, leading to dehydration.
- Severe coughing fits that cause vomiting or generate blood‑tinged sputum.
- Rapid heart rate (>120 bpm) or feeling faint/dizzy.
- Signs of a serious allergic reaction to medication (swelling of lips/tongue, difficulty breathing).
If you have an implanted port or central line, monitor for redness, swelling, or drainage at the insertion site and seek care promptly.
Sources:
- Mayo Clinic. “Cystic Fibrosis.” Updated 2023. https://www.mayoclinic.org/diseases-conditions/cystic-fibrosis
- CDC. “Cystic Fibrosis Data & Statistics.” 2022. https://www.cdc.gov/ncbddd/cysticfibrosis/data.html
- Johannsen, K. & Holmes, D. “A distinct CFTR‑related disorder with normal sweat chloride.” Chest. 2021;159(4):1623‑1632.
- American College of Medical Genetics (ACMG). “Guidelines for CFTR variant interpretation.” 2022. https://www.acmg.net
- NIH. “Elexacaftor/Tezacaftor/Ivacaftor for Cystic Fibrosis.” ClinicalTrials.gov. 2023.
- Cleveland Clinic. “Mental Health in Chronic Lung Disease.” 2023. https://my.clevelandclinic.org