Genetic susceptibility to neonatal lung diseases.

Advances in molecular genetics have enabled improvement of knowledge in pathogenesis and diagnosis of either monogenic or multifactorial neonatal lung diseases. Variants in genes regulating surfactant function and metabolism are implicated in some rare and common respiratory diseases. Congenital surfactant deficiencies are rare diseases due to mutations in genes encoding surfactant proteins and cause significant and often lethal respiratory failure in newborns and interstitial lung disease in older children. Diagnosis is made by molecular analysis and eventually confirmed by histological analysis of lung tissue. A multifactorial contribution, resulting from interaction between multiple genes and environmental factors, has been supposed for respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD). Several potential candidate genes, especially regarding surfactant proteins and cytokines, have been shown in association with these diseases. Genetic variants predisposing to RDS or BPD are usually polymorphisms which are not causative, but can increase susceptibility to the disease. Identification of infants at risk of disease can be useful to provide them individualized therapies. (www.actabiomedica.it).

Preterm birth and metabolic implications on later life: A narrative review focused on body composition.

Preterm newborn infants are characterized by low body weight and lower fat mass at birth compared with full-term newborn neonates. Conversely, at term corrected age, body fat mass is more represented in preterm newborn infants, causing a predisposition to developing metabolic syndrome and cardiovascular diseases in later life with a different risk profile in men as compared with women. Postnatal growth is a complex change in anthropometric parameters and body composition. Both quantity and quality of growth are regulated by several factors such as fetal programming, early nutrition, and gut microbiota. Weight gain alone is not an optimal indicator of nutritional status as it does not accurately describe weight quality. The analysis of body composition represents a potentially useful tool to predict later metabolic and cardiovascular risk as it detects the quality of growth by differentiating between fat and lean mass. Longitudinal follow-up of preterm newborn infants could take advantage of body composition analysis in order to identify high-risk patients who apply early preventive strategies. This narrative review aimed to examine the state-of-the-art body composition among born preterm children, with a focus on those in the pre-school age group.

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

OBJECTIVE: Genetic 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 METHODS: A 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. RESULTS: Heterozygous 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. DISCUSSION: Rare 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.

Unexplained neonatal respiratory distress due to congenital surfactant deficiency.

Genetic abnormalities of pulmonary surfactant were identified by DNA sequence analysis in 14 (12 full-term, 2 preterm) of 17 newborn infants with fatal respiratory distress of unknown etiology. Deficiency of adenosine triphosphate-binding cassette protein, member A3 (n = 12) was a more frequent cause of this phenotype than deficiency of surfactant protein B (n = 2).

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.

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.

[Genetic basis in chronic interstitial familial pneumopathy. Familial study of SFTPC]. / Basi genetiche della pneumopatia cronica interstiziale familiare. Studio familiare dell'SFTPC.

Mutations in the gene encoding surfactant protein C (SP-C) SFTPC have been found to be associated with chronic interstitial lung disease. A 5-year-old girl oxygen dependent from birth and affected by interstitial lung disease (ILD) is heterozygous for a T to C change in exon 3 resulting in the substitution of threonine for isoleucine at codon 73 (173T), already described in association with ILD. We studied 25 members of her family where the 173T mutation in the SP-C gene is associated to chronic pulmonary diseases. Five members in the mother's family showed respiratory diseases with great diversity in clinical features: her mother was affected by restrictive pneumopathy and emphysema, her grand-mother by asthma and recurrent pneumonia, 2 uncles underwent lung transplantation in the adult age, an aunt was clinically diagnosed having pulmonary fibrosis. All the family members affected by pulmonary diseases and one with no clinical symptoms showed the presence of the mutation 173T. Among the other family members the mutation was found in six subjects for whom no clinical data were available, yet. Our results confirm that heterozygosity for the mutation 173T may cause chronic inflammation of the lung or progressive pulmonary fibrosis. In addition, the possibility to study a large pedigree allowed us to perform a genotype-phenotype correlation indicating a marked phenotypic variability. The diversity in symptoms, age at onset, clinical course, duration of lung disease in the relatives sharing this mutation indicates an incomplete penetrance of the mutation. This might be due to the influence of other genetic factors thus indicating that the phenotype may be complicated by additional components.

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.

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 beta 2-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 alpha-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.

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). The clinical records of the siblings were examined; the genes encoding surfactant protein B (SFTPB), surfactant protein C (SFTPC), and ATP-binding cassette transporter 3 protein (ABCA3) were analyzed with direct sequencing and Southern blotting. The infants were homozygous for a 5,983 bp deletion in ABCA3 including exons 2-5 as well as the start AUG codon and a putative Golgi exit signal motif. Dense abnormalities of lamellar bodies at electron microscopy and absence of ABCA3 at immunohistochemical staining were in agreement with the presence of two null alleles. In addition, an increased lipid synthesis suggested a compensatory mechanism. The clinical course in the two sisters was influenced by different environmental factors like the time needed for molecular confirmation, the ventilatory assistance adopted, the occurrence of infections. A less aggressive clinical approach did not improve the course of the disease; the prognosis was always poor. Development of a fast molecular test, able to detect also structural variants, is needed.

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.

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.

A common mutation in the surfactant protein C gene associated with lung disease.

OBJECTIVE: To determine the contribution of the surfactant protein C (SP-C) I73T mutation to lung disease. STUDY DESIGN: Genomic DNA was obtained from 116 children with interstitial lung disease (ILD) or chronic lung disease of unclear cause and from 166 control subjects and was screened for the I73T mutation using an allele-specific polymerase chain reaction assay. RESULTS: The I73T mutation was found on 7 of 232 SP-C alleles from 7 unrelated children with ILD but was not found on 332 control SP-C alleles ( P < .01, Fisher exact test). The I73T mutation segregated with lung disease in one kindred with familial ILD. The I73T mutation was found in an asymptomatic parent from two different families with affected children consistent with variable penetrance, but it was not found in either asymptomatic parent of two other unrelated affected children consistent with a de novo mutation. Analysis of single nucleotide polymorphisms indicated diverse genetic backgrounds of the I73T alleles. Immunohistochemical analysis of lung tissue from an infant with the I73T mutation demonstrated normal staining patterns for proSP-B, SP-B, and proSP-C. CONCLUSIONS: These findings support the hypothesis that the I73T mutation predisposes to or causes lung disease.