To the Editor:
Since the advent of the Human Genome Project, opening doors to an era of genomic medicine, the family history has become a relevant and critical tool in individualized disease prevention. The family history has lasted through the years as a key component of history-taking in medical education. Yet it continues to be underutilized owing to barriers in time and infrastructure, much due to the common underestimation of its value.1Â We report a case of recurrent pneumonia in which the suspicion of non-classic cystic fibrosis was predicated upon the clinical presentation, the family history, and findings of bronchiectasis on lung imaging.
Case Presentation
A 52-year-old woman presented with cough after multiple hospitalizations for the past 2 months for pneumonia. After her most recent hospitalization her symptoms improved, but over the preceding 4 days she had complained of dyspnea and productive cough. Additionally, she reported generalized weakness, steatorrhea, and inability to gain weight. Her past medical history was significant for chronic pancreatitis, rectal prolapse, failure to thrive, and multiple pneumonias requiring antibiotics. Upon interrogation of her family history it was revealed that her granddaughter had screened positive for cystic fibrosis on newborn screening, and she had 3 maternal second cousins with cystic fibrosis. On presentation she was hypoxemic with an oxygen saturation of 74% on room air, which improved to the 90% range on 2 L of oxygen by nasal cannulation, with a respiratory rate of 22 breaths per minute. Her body mass index was 16.1 kg/m2Â on admission and had ranged from 15 kg/m2Â to 18 kg/m2Â over the 2 years prior to presentation.
Chest computed tomography (Figure) showed central bronchiectasis with mucus plugging, as well as bilateral scattered opacities. She underwent bronchoscopy, which yielded cultures positive for methicillin-sensitive Staphylococcus aureus. She was initiated on antibiotics with cefazolin, which was transitioned to oral levofloxacin upon discharge from the hospital. On outpatient follow-up, pulmonary function tests were notable for a forced expiratory volume at 1 second (FEV1) of 69% predicted, forced vital capacity (FVC) of 85% predicted, FEV1/FVC of 64%, and forced expiratory flow at 25%-75% of FVC of 34% predicted. Stool pancreatic elastase-1 was low at 28 μg/g. A sweat test showed borderline values of 40 mmol/L on the left side and 34 mmol/L on the right side, and genetics testing revealed 1 copy of the δ-F508 mutation, as well as another change, K1080Q of uncertain clinical significance. Repeat expanded genetic analysis did not show any additional known mutations. She was subsequently diagnosed with non-classic cystic fibrosis.
Discussion
Cystic fibrosis is an autosomal recessive disorder leading to severe pulmonary disease, which can be associated with multiorgan involvement due to mutations in the CFTR gene. Cystic fibrosis is typically diagnosed in childhood, with newborn screening becoming the norm, although interestingly, approximately 2% of these patients make up a subgroup known as non-classic cystic fibrosis.2 As the gold standard for the diagnosis of cystic fibrosis, sweat chloride testing of classic cystic fibrosis is defined by sweat chloride concentrations >60 mmol/L; in non-classic cystic fibrosis, however, sweat chloride concentrations range from normal (<30 mmol/L) to borderline (30-60 mmol/L).3 Genetic testing of patients with cystic fibrosis typically demonstrates 2 CFTR gene mutations. Non-classic cystic fibrosis is becoming increasingly recognized in adolescents and adults, but the diagnosis is not a simple one, given the heterogeneity of presentation and variability in multiorgan involvement outweighing costs of expensive genetic testing. Cystic fibrosis is clinical diagnosis that, in this case, was driven predominantly by the strong family history as well as the presenting symptoms. This case reinforces the spectrum of cystic fibrosis and the importance and value of a thorough family history and clinical evaluation.
To read this article in its entirety please visit our website.
-Justin K. Lui, MD, Joseph Kilch, MD, Svetlana Fridlyand, DO, Abduljabbar Dheyab, MBChB, Christine Bielick Kotkowski, MD
This article originally appeared in the August 2017 issue of The American Journal of Medicine.
