CASE 2:
A female neonate was born vaginally at 36 weeks’ gestation with right full lip cleft. She was transported to our hospital due to cyanosis from birth. Although the echocardiogram showed aortic valve regurgitation, moderate pulmonary hypertension, and PDA; she was discharged without desaturation at 11 days old. She was admitted with poor feeding at 4 weeks old, and her oxygen saturation in room air fell to 83%. Chest CT showed partial atelectasis in dorsal predominance and most of the right upper lobe. Lobular emphysematous changes with hyperinflation were observed in both lungs. The echocardiogram revealed a 2.5-mm PDA with a left-to-right shunt, and exacerbation of pulmonary hypertension. Sildenafil was administered for pulmonary hypertension. Her respiratory symptoms deteriorated, and she was intubated and ventilated. She was briefly extubated, but she required reintubation due to respiratory failure and ventilatory support. Cardiac catheterization revealed a pulmonary artery pressure of 46/27 mmHg (mean, 36 mmHg). Pulmonary hypertension was suspected as the cause of the recurring breathing problems, so she underwent PDA ligation. She was successfully weaned off the ventilator and discharged at 8 months old on 0.5 L/min of oxygen. After the left-to-right shunt had closed, her NT-proBNP value reduced from 8,973 pg/mL to 312 pg/mL. Whole exome sequencing analysis was performed and detected a nonsense mutation c.7231C>T:p.(Arg2411*) in the FLNA gene.
We report two girls with FLNA mutation and both ILD and left-to-right shunts due to CHD who had difficulty in managing their respiration but showed improved respiratory status after shunt closure. Partnership with the cardiology, cardiovascular surgery, and intensive care departments led to successful treatment.
Respiratory disorders associated with FLNA mutation can be lethal. Some children have died of infection and respiratory failure, and others have received lung transplantation in Europe and the United States[2, 3].Our cases were primarily treated as hypoxia due to lung disease and the patients initially were administered with oxygen and pulmonary vasodilators. However, the respiratory status of both patients worsened, which could be attributed to not only ILD but also pulmonary over-circulation.
Pathological findings of the lung associated with FLNA mutations have been reported in the lung parenchyma with alveolar simplification and pulmonary artery curvature[3]. The increase in volume loading for poor vascular beds is seen in ILD with pulmonary hypertension. It is our opinion that as filamin A is capable of repairing tissues, its mutation could result in lung damage. Both patients showed improved breathing conditions after closing the small left-to-right shunts and were consequently discharged.
Pulmonary hypertension is a common comorbidity with ILD and is associated with a substantially increased mortality risk[4]. Our cases were complicated by pulmonary hypertension and CHD. High NT-proBNP levels are associated with a poor prognosis in ILD patients[5]. The NT-proBNP value of our cases decreased following shunt closure. The postoperative reduction in the cardiac volume load caused by the shunt suggested that pulmonary congestion improved, suggesting that NT-proBNP could also be used as a biomarker in this disease.
Despite the seemingly unrelated treatment between respiratory failure and heart failure, the outcome of our cases suggests that aggressive shunt closure intervention, even if the shunt is small, can improve the condition of lung damage and the prognosis of patients with lung disease associated with FLNA mutation.
Acknowledgements: This work was supported by the Initiative on Rare and Undiagnosed Diseases(19ek0109301) and MGeND (Medical Genomics Japan Variant Database(19kk020514) from the Japan Agency for Medical Research and Development and JSPS KAKENHI 20K08270(K.K.).
Conflict of interest: None
Reference
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Image legend: Axial chest computed tomography images of Case 1 of a) the upper b) and lower at four months of age show partial atelectasis in the bilateral dorsal region and hyperinflation in the upper lobe. Serial chest radiographs at c) four months, d) eight months, and e) one year of age reveal improvement in hyperinflation and atelectasis.