CASE PRESENTATION:
This 530 gm female newborn was delivered to a G1P0 female by an emergency cesarean-section due to eclampsia at 25 weeks’ gestation. She was rapidly intubated at birth, treated with exogenous surfactant, placed on conventional mechanical ventilation in the NICU and subsequently transferred to a level III medical center. Her early course was characterized by profound hypoxemic respiratory failure with severe PH. Throughout her course, serial echocardiograms demonstrated signs of supra-systemic PA pressures with RV hypertrophy and dilation. The infant was managed with high frequency and conventional ventilation initially but failed to tolerate extubation and non-invasive respiratory support at 45 weeks GA. Despite aggressive therapy which included use of PH-targeted therapies, her hypoxemia continued to worsen along with frequent cyanotic episodes. A tracheostomy was performed to support longer-term invasive ventilation. Serial chest radiographs revealed progressive hyperinflation with heterogenous regions of patchy atelectasis and infiltrates with regional over-distension. , Her course worsened with increased severity of cyanotic episodes due to progressive worsening of her chronic lung disease and PH. After extensive discussions with the family, the decision to redirect care due to futility was made and the child died. The family agreed to a limited heart and lung autopsy as well as clinical exome sequencing (ES) to identify genetic variants associated with known developmental lung diseases.
ES at Prevention Genetics revealed the following heterozygous variants of uncertain significance: c.2929G>A (p.Glu977Lys) and c.3019G>A (p.Gly1007Ser) in APC2 , c.4451C>G (p.Ser1484Cys) in KAT6B , and c.664G>A (p.Ala222Thr) in KMT2D . Histopathology findings were consistent with sBPD with marked pulmonary hypertensive remodeling and prominent IBA. (FIGURE 1 A+B ) As these features are also compatible with the diagnosis of ACDMPV, additional genetic and molecular analyses were performed from the lung tissue using Sanger sequencing, genome wide array CGH, and RT-qPCR. No evidence of point mutations nor CNV deletions involving FOXF1 or TMEM100 was found.
Real Time-qPCR measurements were performed in triplicates using as a control normal lung tissue specimen from three age-matched individuals. RNA from the frozen lung autopsy specimen was extracted using miRNeasy Mini Kit Isolated RNA was reverse-transcribed using SuperScript III First-Strand Synthesis System TaqMan gene expression assays were obtained from Applied Biosystems. RT-qPCRs were done using TaqMan Universal PCR Master Mix For relative transcript quantification, the comparative CT method was used. FOXF1 and TMEM100transcript levels were normalized to that of GAPDH . The expressions were calculated relative to one of the controls. Remarkably, transcript levels of FOXF1 and TMEM100 are significantly reduced in the lungs of the proband, resembling those seen in patients with FOXF1 deficiency due to pathogenic CNV deletion. (FIGURE 1 C+D )