Marco Somaschini

Exome sequencing and pathway analysis for identification of genetic variability relevant for bronchopulmonary dysplasia (BPD) in preterm newborns: A pilot study

BACKGROUND Bronchopulmonary dysplasia (BPD) is the most common chronic lung disease in infancy, affecting preterm children with low birth weight. The disease has a multifactorial aetiology with a significant genetic component; until now published association studies have identified several candidate genes but only few of these data has been replicated. In this pilot study, we approached exome sequencing aimed at identifying non-common variants, which are expected to have a stronger phenotypic effect. MATERIALS AND METHODS We performed this study on 26 Italian severely affected BPD preterm unrelated newborns, homogeneously selected from a large prospective cohort. We used an Illumina HiSeq 2000 for sequencing. Data analysis was focussed on genes previously associated to BPD susceptibility and to new candidates in related pathways, highlighted by a prioritization analysis performed using ToppGene Suite. RESULTS By exome sequencing, we identified 3369 novel variants, with a median of 400 variations per sample. The top candidate genes highlighted were NOS2, MMP1, CRP, LBP and the toll-like receptor (TLR) family. All of them have been confirmed with Sanger sequencing. CONCLUSIONS Potential candidate genes have been discovered in this preliminary study; the pathogenic role of identified variants will need to be confirmed with functional and segregation studies and possibly with further methods, able to evaluate the collective influence of rare variants. Moreover, additional candidates will be tested and genetic analysis will be extended to all affected children.

Genetic predisposing factors to bronchopulmonary dysplasia: preliminary data from a multicentre study

Bronchopulmonary dysplasia (BPD) is the most frequent chronic lung disease in preterm newborn infants. It is a multifactorial disease caused by the interaction between environmental and genetic factors. The aim of this study is to identify genetic variants contributing to BPD development using next-generation sequencing (NGS) technology. We prospectively evaluated 378 premature newborn infants with a gestational age <32 weeks in a multicentre study from 12 Italian neonatal intensive care unit from 2009 to 2012. Infants were divided into two groups: normal controls (225) and BPD-affected infants (141) with mild (65, 46.1%), moderate (40, 28.4%) and severe (36, 25.5%) BPD. BPD was more frequent in infants with lower weight and gestational age. Antenatal steroid administration was more frequent in the control group. Postnatal infection, respiratory distress syndrome, patent ductus arterious, cerebral haemorrhage, surfactant administration, ventilatory support, diuretics and postnatal steroid administration correlated with severity of BPD. Among BPD, moderate and severe cases will be selected as BPD “extreme phenotypes”, and in fact variations in 28-day oxygen need-based BPD were previously shown to be fully attributable to environmental effects whereas dependence on supplemental oxygen at 36 weeks seems to better reflect underlying genetic susceptibility. Exome analysis by NGS is in progress. Identifications of genetic markers predisposing to BPD may allow development of personalized and preventive treatments.

Congenital misalignment of pulmonary vessels and alveolar capillary dysplasia: how to manage a neonatal irreversible lung disease?

Congenital misalignment of pulmonary vessels (MPV) with alveolar capillary dysplasia is a rare condition consisting of anomalous veins in bronchovascular bundles, a decreased number of alveolar capillaries, and increased muscularization of pulmonary arterioles. In the literature, infants reported as having such a malformation developed respiratory distress with persistent pulmonary hypertension and ultimately died. We report the case of an infant with MPV and alveolar capillary dysplasia who was unresponsive to maximal cardiorespiratory support, including high-frequency oscillatory ventilation and inhaled nitric oxide; the infant died of pulmonary hemorrhage after 19 days, during venoarterial extracorporeal membrane oxygenation bypass. We conclude that the diagnosis of MPV and alveolar capillary dysplasia should be considered during autopsy of infants who have died of irreversible persistent pulmonary hypertension. If a lung biopsy in infants with prolonged refractory hypoxemia confirms such diagnosis before death, expensive and invasive treatments such as extracorporeal membrane oxygenation could be avoided.

The Fanconi–Bickel Syndrome: a Case of Neonatal Onset

A male newborn infant was recognized having Fanconi–Bickel syndrome (FBS) in the neonatal period. The presenting clinical findings were hyperglycemia and polyuria detected during an episode of acute enteritis. Physical examination was normal, biochemical analyses were suggestive of FBS: glycosuria, proteinuria, phosphaturia, generalized aminoaciduria, and increased levels of urinary β2-microglobulin, serum glucose and serum alkaline phosphatase. The molecular genetic analysis showed homozygosity for mutations within the gene of the glucose transporter 2 (Glut 2), 1213 C>T. The patient demonstrated improved clinical and metabolic status following institution of diet with frequent small meals and galactose-free-milk as well as pharmacological treatment with phosphate and vitamin α-OH-D3. In conclusion, infants showing hyperglycemia and polyuria may be considered having FBS also in the neonatal period. Early institution of adequate caloric intake and replacement of electrolytes and vitamin D may avoid or reduce metabolic complications.

Inhaled NO and Markers of Oxidant Injury in Infants with Respiratory Failure

BACKGROUND:Inhaled nitric oxide (iNO) is an effective adjunct in the treatment of infants with respiratory failure. Although there are clear benefits to this therapy, potential toxicity could result from reactive nitrosylated species.OBJECTIVE:To evaluate whether iNO therapy is associated with increased serum markers of oxidative stress.DESIGN/METHOD:Multiple markers were prospectively evaluated in the serum of term infants with severe respiratory failure treated with iNO for 1 to 72 hours. These were compared to those of patients exposed to greater than 80% oxygen for more than 6 hours and room air controls.RESULTS:After 24 hours of exposure, the iNO-treated infants had increased serum lipid hydroperoxides (LPO), protein carbonyls and nitrotyrosine residues as well as increased serum total glutathione (GSH) content. The increase in LPO peaked at 24 hours and correlated with the cumulative dose of iNO whereas other markers did not. The presence of chronic lung disease (CLD) did not correlate with serum markers of oxidative injury.CONCLUSIONS:In term infants with respiratory failure, prolonged iNO exposure is associated with a transient increase in markers of oxidative stress, but this finding does not appear to predict the development of CLD.

Fatal respiratory failure in a full-term newborn with two ABCA3 gene mutations: a case report

Genetic mutations associated with pulmonary surfactant protein deficiency are associated with diverse clinical phenotypes. Mutations of the surfactant protein B and C genes were the first to be described. In 2004, fatal surfactant deficiency in newborns due to mutations of the gene encoding the adenosine triphosphate-binding cassette transporter A3 (ABCA3) was first reported. Few cases of lethal adenosine triphosphate-binding cassette transporter A3 mutations have been described to date. In our report, we describe a full-term newborn that died because of respiratory failure secondary to an uncommon ABCA3 genetic configuration.

Null ABCA3 in humans: Large homozygous ABCA3 deletion, correlation to clinical-pathological findings

A study was undertaken to analyze the clinical presentation, pulmonary function, and pathological features in two female siblings with neonatal pulmonary surfactant metabolism dysfunction, type 3 (MIM 610921).

Familial Clustering of Unexplained Transient Respiratory Distress in 12 Newborns from Three Unrelated Families Suggests an Autosomal-Recessive Inheritance

We report on 12 near-term babies from three families in which an unexplained transient respiratory distress was observed. No known risk factor was present in any family and no sequelae were recorded at follow-up. The most common causes of respiratory distress at birth are Neonatal Respiratory Distress Syndrome (NRD) and Transient Tachypnea of the Newborn (TTN), and their cumulative incidence is estimated to be about 2%. Genetic factors have been identified in NRD (surfactant genes) or suggested for TTN (genes affecting lung liquid clearance). Survivors from NRD may develop clinically relevant sequelae, while TTN does not cause any problem later in life. Our cases do not immediately fit NRD or TTN, while familial recurrence suggests the existence of a previously unreported subgroup on patients with respiratory distress for which autosomal-recessive inheritance is likely.

Preterm birth, respiratory failure and BPD: Which neonatal management?

Preterm birth is a significant problem in the world regarding perinatal mortality and morbidity in the long term, especially bronchopulmonary dysplasia (BPD). Premature delivery is often associated to failure in transition to create an early functional residual capacity (FRC), since many preterm babies need frequently respiratory support. The first and most effective preventive measure to reduce the incidence of BPD is represented by the attempt to avoid preterm birth. Whenever this fails, the prevention of every known risk factors for BPD should start in the delivery room and should be maintained in the NICU through the use of tailored management of high-risk infants.

Surfactant proteins gene variants in premature newborn infants with severe respiratory distress syndrome

ObjectiveGenetic surfactant dysfunction causes respiratory failure in term and near-term newborn infants, but little is known of such condition in prematures. We evaluated genetic surfactant dysfunction in premature newborn infants with severe RDS.Patients and methodsA total of 68 preterm newborn infants with gestational age ≤32 weeks affected by unusually severe RDS were analysed for mutations in SFTPB, SFTPC and ABCA3. Therapies included oxygen supplementation, nasal CPAP, different modalities of ventilatory support, administration of exogenous surfactant, inhaled nitric oxide and steroids. Molecular analyses were performed on genomic DNA extracted from peripheral blood and Sanger sequencing of whole gene coding regions and intron junctions. In one case histology and electron microscopy on lung tissue was performed.ResultsHeterozygous previously described rare or novel variants in surfactant proteins genes ABCA3, SFTPB and SFTPC were identified in 24 newborn infants. In total, 11 infants died at age of 2 to 6 months. Ultrastructural analysis of lung tissue of one infant showed features suggesting ABCA3 dysfunction.DiscussionRare or novel genetic variants in genes encoding surfactant proteins were identified in a large proportion (35%) of premature newborn infants with particularly severe RDS. We speculate that interaction of developmental immaturity of surfactant production in association with abnormalities of surfactant metabolism of genetic origin may have a synergic worsening phenotypic effect.