Lung hypoplasia and its associated major congenital abnormalities in perinatal death: an autopsy study of 850 cases

Mesenchyme-specific deletion of Tgf-β1 in the embryonic lung disrupts branching morphogenesis and induces lung hypoplasia

Proper lung development depends on the precise temporal and spatial expression of several morphogenic factors, including Fgf10, Fgf9, Shh, Bmp4, and Tgf-β. Over- or under-expression of these molecules often leads to aberrant embryonic or postnatal lung development. Herein, we deleted the Tgf-β1 gene specifically within the lung embryonic mesenchymal compartment at specific gestational stages to determine the contribution of this cytokine to lung development. Mutant embryos developed severe lung hypoplasia and died at birth due to the inability to breathe. Despite the markedly reduced lung size, proliferation and differentiation of the lung epithelium was not affected by the lack of mesenchymal expression of the Tgf-β1 gene, while apoptosis was significantly increased in the mutant lung parenchyma. Lack of mesenchymal expression of the Tgf-β1 gene was also associated with reduced lung branching morphogenesis, with accompanying inhibition of the local FGF10 signaling pathway as well as abnormal development of the vascular system. To shed light on the mechanism of lung hypoplasia, we quantified the phosphorylation of 226 proteins in the mutant E12.5 lung compared with control. We identified five proteins, Hrs, Vav2, c-Kit, the regulatory subunit of Pi3k (P85), and Fgfr1, that were over- or under-phosphorylated in the mutant lung, suggesting that they could be indispensable effectors of the TGF-β signaling program during embryonic lung development. In conclusion, we have uncovered novel roles of the mesenchyme-specific Tgf-β1 ligand in embryonic mouse lung development and generated a mouse model that may prove helpful to identify some of the key pathogenic mechanisms underlying lung hypoplasia in humans.

Siblings with lethal primary pulmonary hypoplasia and compound heterozygous variants in the AARS2 gene: further delineation of the phenotypic spectrum

Variants in the mitochondrial alanyl-tRNA synthetase 2 gene AARS2 (OMIM 612035) are associated with infantile mitochondrial cardiomyopathy or later-onset leukoencephalopathy with premature ovarian insufficiency. Here, we report two newborn siblings who died soon after birth with primary pulmonary hypoplasia without evidence of cardiomyopathy. Whole-exome sequencing detected the same compound heterozygous AARS2 variants in both siblings (c.1774C>T, p.Arg592Trp and c.647dup, p.Cys218Leufs*6) that have previously been associated with infantile mitochondrial cardiomyopathy. Segregation analysis in the family confirmed carrier status of the parents and an unaffected sibling. To our knowledge, this is the first report of primary pulmonary hypoplasia in the absence of cardiomyopathy associated with recessive AARS2 variants and further defines the phenotypic spectrum associated with this gene.

An autopsy based descriptive study of the spectrum of pulmonary lesions encountered in fetal deaths at a tertiary care center

Background

: Fetal autopsy has been an indispensable tool in evaluating the cause of death. The most common cause for fetal deaths is associated with respiratory disorders accounting for around 60%. This study was undertaken to evaluate the gross and microscopic features of lungs in fetal autopsies and estimate the incidence of deaths attributable to pulmonary causes.

Materials and Methods

: All fetuses received for autopsy at our institute were included in the study with prior consent. Gross and microscopic findings along with relevant clinical data were recorded.

Results

A total of 426 autopsies were conducted from January 2011 to August 2016. Of those, 184 had abnormal pulmonary findings constituting 43.19%. Aspiration pneumonia was the most common finding with 67 cases (36.4%), followed by atelectasis 54 cases (29.3%), congenital cystic adenomatoid malformation in 13 cases (7.1%), lung hypoplasia 12 cases (6.5%), pulmonary hemorrhage 21 (11.4%), 15 cases (8.15%) of hyaline membrane disease, one case (0.5%) of heterotaxy, and one case of extralobar pulmonary sequestration (0.5%). Congenital malformations of lungs were seen in 27 (14.67%) cases and 38 cases (20.65%) had other associated anomalies.

Conclusion

Pulmonary pathology is the most common finding in fetal deaths with aspiration pneumonitis being the most common avoidable cause. Accurate fetal autopsy along with clinical data are important in evaluating fetal deaths and can help in reduction of unexplained stillbirths.

Clinical cardiac assessment in newborns with prenatally diagnosed intrathoracic masses

Background

Congenital space-occupying thoracic malformations and diaphragmatic hernia have in common pulmonary hypoplasia. Our study aims to assess cardiac involvement during post-natal adaptation.

Methods

A retrospective study was carried out on newborns with prenatally diagnosed intrathoracic mass. Gathering for respiratory distress syndrome (RDS), 35 neonates were compared for clinical course, cardiovascular enzymes, ECG, and ultrasound.

Results

The analysis revealed a high left heart defect rate in patients with severe RDS, without being influenced by the laterality. Ultrasound or laboratory assessment did not detect altered cardiac dimension or cardiomyopathy. Solely ECG signs of right ventricular strain were found. Increased QT-dispersion, T-wave and cardiac variability alterations in the first hours were all expression of non-specific cardiac repolarization disorders but predict worse outcome.

Conclusions

Although RDS is the predominant symptom, slight cardiac dysfunctions should be recognized for prompt treatment. Conventional examinations for postnatal adaption should be integrated by complementary investigations.

High-output cardiac failure in a fetus with thanatophoric dysplasia associated with large placental chorioangioma: case report

Placental chorioangioma is an angioma arising from chorionic tissue. Fetal thanatophoric dysplasia is a lethal skeletal dysplasia due to mutation of fibroblast growth factor receptor 3 gene. These two conditions are rare and their coexistence in a given fetus is even rarer. We present a case of a fetus with thanatophoric dysplasia having high-output cardiac failure due to a large placental chorioangioma.

Unilateral primary pulmonary agenesis and hypoplasia in monozygotic twins

We describe 10-month-old identical female twin infants, one with primary left-sided pulmonary agenesis and the other with primary left-sided pulmonary hypoplasia. They came to our outpatient clinic complaining of persistent dry cough. The clinical examination revealed decreased air entry over the left hemithorax. Chest x-rays showed complete left-sided radio-opacity in both the twins. The chest computed tomography scan with contrast confirmed the diagnoses of left-sided pulmonary agenesis (twin A) and left-sided hypoplasia (twin B). No other associated congenital anomaly was noted in either of the twins. To our knowledge, such a condition in live monozygotic twins has not been previously reported in published studies.

Respiratory and general outcome in neonates with renal oligohydramnios--a single-centre experience

BACKGROUND

Renal oligohydramnion (ROH) is predominantly caused by congenital abnormalities of the kidney and urogenital tract (CAKUT). Although the number of neonates born with chronic renal failure is small, they provide many challenges, and among the most problematic are respiratory management and long-term treatment of chronic renal failure. We studied the value of prenatal and perinatal variables to predict survival and the general long-term outcome of our ROH population. Method. A single-centre retrospective chart review was conducted in 36 neonates with ROH treated between 1996 and 2007. Respiratory data sets including minimum inspiratory oxygen concentration (FiO(2), 1d), best oxygenation index (BOI, 1d) and minimum arterial partial carbon dioxide (pCO(2), 1d) at the first day of life were available in 23 children requiring intubation.

RESULTS

ROH causes were obstructive uropathy (n = 19), polycystic kidney disease [autosomal recessive polycystic kidney disease (ARPKD) n = 5 and autosomal dominant polycystic kidney disease n = 1], renal agenesis/dysplasia (n = 10) and bilateral renal vein thrombosis (n = 1). Survival until discharge was 64% (23/36), and overall survival was 58% (21/36). Seven patients died within 48 h from respiratory failure. Non-survivors had a higher minimum FiO(2) and pCO(2) (1d) compared to survivors (P < 0.001). Mean BOI (1d) was 6.2 in survivors versus 43.9 in the non-surviving group (P < 0.001). Logistic regression showed that BOI (</≥ 9.6) and first diagnosis of ROH (≤/>28 gestational weeks) retained significance in predicting survival until discharge.

CONCLUSIONS

The attitude toward initiating dialysis in neonates is changing and long-term outcome in the absence of severe comorbidity is promising. Prenatal prediction concerning respiratory and renal outcome in fetuses with ROH is difficult. Our data suggest that BOI (1d) and onset of ROH may be reliable predictors of respiratory prognosis in children born with ROH.