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 )