A child with severe pneumomediastinum and ABCA3 gene mutation: a puzzling connection

ABCA3

BACKGROUND

The majority of patients with childhood interstitial lung disease (chILD) caused by pathogenic variants in ATP binding cassette subfamily A member 3 (ABCA3) develop severe respiratory insufficiency within their first year of life and succumb to disease if not lung transplanted. This register-based cohort study reviews patients with ABCA3 lung disease who survived beyond the age of 1 year.

METHOD

Over a 21-year period, patients diagnosed as chILD due to ABCA3 deficiency were identified from the Kids Lung Register database. 44 patients survived beyond the first year of life and their long-term clinical course, oxygen supplementation and pulmonary function were reviewed. Chest CT and histopathology were scored blindly.

RESULTS

At the end of the observation period, median age was 6.3 years (IQR: 2.8-11.7) and 36/44 (82%) were still alive without transplantation. Patients who had never received supplemental oxygen therapy survived longer than those persistently required oxygen supplementation (9.7 (95% CI 6.7 to 27.7) vs 3.0 years (95% CI 1.5 to 5.0), p=0.0126). Interstitial lung disease was clearly progressive over time based on lung function (forced vital capacity % predicted absolute loss -1.1% /year) and on chest CT (increasing cystic lesions in those with repetitive imaging). Lung histology pattern were variable (chronic pneumonitis of infancy, non-specific interstitial pneumonia, and desquamative interstitial pneumonia). In 37/44 subjects, the ABCA3 sequence variants were missense variants, small insertions or deletions with in-silico tools predicting some residual ABCA3 transporter function.

CONCLUSION

The natural history of ABCA3-related interstitial lung disease progresses during childhood and adolescence. Disease-modifying treatments are desirable to delay such disease course.

Clinical course and long-term follow-up of a preterm infant with non-fatal respiratory distress syndrome due to heterozygous ABCA3 gene mutation: A case report and review of literature

BACKGROUND

Adenosine triphosphate-binding cassette transporter A3 (ABCA3) mutations are recognized as a congenital cause of surfactant deficiency. Clinical presentations of such mutations are largely variable. There are many mutations of the ABCA3 gene, of which, p.E292V is the most common. Despite being the most common ABCA3 gene mutation, there is limited literature on extra pulmonary and long-term outcomes of the affected infants.

CASE

We present the case of a Caucasian male infant born at 32 weeks gestation that developed severe respiratory distress shortly after birth, and review published case reports and case series of infants affected with this gene mutation. He was found to have a heterozygous missense mutation p.E292V of ABCA3 resulting in a chronic lung disease. He required multiple courses of systemic and inhalational steroids. He developed supraventricular tachycardia (SVT), feeding problems and hypotonia during his prolonged hospital stay. He demonstrated mild neurodevelopmental delays on follow up at 18 months of age. The chronic lung disease improved over the first 2 years of life. He continued to have feeding difficulties and supraventricular tachycardia at nearly 2 years of age.

CONCLUSION

The infant's SVT may be associated with this ABCA3 variant. Further long-term follow-up studies are needed to better characterize extrapulmonary manifestations of this ABCA3 mutation.

Three Infants with Pathogenic Variants in the ABCA3 Gene: Presentation, Treatment, and Clinical Course

ABCA3 deficiency is a rare cause of neonatal respiratory failure. Biallelic complete loss of function variants lead to neonatal demise without lung transplantation, but children with partial function variants have variable outcomes. The favorable clinical course of 3 such infants presenting with respiratory distress at birth is described.

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.