A New ABCA3 Gene Mutation c.3445G>A (p.Asp1149Asn) as a Causative Agent of Newborn Lethal Respiratory Distress Syndrome

ABCA3 c.838C>T (p.Arg280Cys, R280C) and c.697C>T (p.Gln233Ter, Q233X, Q233*) as Causative Variants for RDS: A Family Case Study and Literature Review

Background: Respiratory distress syndrome (RDS) is the primary cause of respiratory failure in preterm infants, but it also affects 5-7% of term infants. Dysfunctions in pulmonary surfactant metabolism, resulting from mutations of the lung surfactant genes, are rare diseases, ranging from fatal neonatal RDS to interstitial lung disease, associated with increased morbidity and mortality. This study aims to clarify the clinical significance of ABCA3 variants found in a specific family case, as existing data in the literature are inconsistent. Material and Methods: A family case report was conducted; targeted panel genetic testing identified a variant of the SFTPB gene and two variants of ABCA3 genes. Comprehensive research involving a systematic review of PubMed, Google Scholar databases, and genome browsers was used to clarify the pathogenicity of the two ABCA3 variants found in the index patient. Advanced prediction tools were employed to assess the pathogenicity of the two ABCA3 variants, ensuring the validity and reliability of our findings. Results: The index case exhibited fatal neonatal RDS. Genetic testing revealed the presence of the SFTPB p.Val267Ile variant, which was not previously reported but is a benign variant based on family genetic testing and history. Additionally, two ABCA3 gene variants were identified: c.697C>T, not yet reported, and c.838C>T. These variants were found to affect ABCA3 protein function and were likely associated with neonatal RDS. Prediction tools and data from nine other cases in the literature supported this conclusion. Conclusions: Based on in silico predictors, an analysis of the presented family, and cases described in the literature, it is reasonable to consider reclassifying the two ABCA3 variants identified in the index case as pathogenic/pathogenic. Reclassification will improve genetic counseling accuracy and facilitate correct diagnosis.

Successful bilateral lung transplantation in a five-year-old child with pulmonary interstitial fibrosis caused by an ABCA3 gene mutation

The ATP-binding cassette subfamily A member 3 (ABCA3) protein plays a fundamental role in surfactant homeostasis. Most children with ABCA3 gene mutations develop pulmonary interstitial fibrosis leading to the development of interstitial lung disease. Since traditional medicine does not offer effective therapy, the best option is lung transplantations, especially bilateral lung transplantations. We are reporting the case of a successful bilateral lung transplantation in a five-year-old child with pulmonary interstitial fibrosis caused by ABCA3 gene mutations. This successful transplantation enabled the patient to get rid of chronic cough and tachypnea.

Descriptive and Functional Genomics in Neonatal Respiratory Distress Syndrome: From Lung Development to Targeted Therapies

In this up-to-date study, we first aimed to highlight the genetic and non-genetic factors associated with respiratory distress syndrome (RDS) while also focusing on the genomic aspect of this condition. Secondly, we discuss the treatment options and the progressing therapies based on RNAs or gene therapy. To fulfill this, our study commences with lung organogenesis, a highly orchestrated procedure guided by an intricate network of conserved signaling pathways that ultimately oversee the processes of patterning, growth, and differentiation. Then, our review focuses on the molecular mechanisms contributing to both normal and abnormal lung growth and development and underscores the connections between genetic and non-genetic factors linked to neonatal RDS, with a particular emphasis on the genomic aspects of this condition and their implications for treatment choices and the advancing therapeutic approaches centered around RNAs or gene therapy.

ABCA3 Deficiency-Variant-Specific Response to Hydroxychloroquine

Biallelic variants in ABCA3, the gene encoding the lipid transporter ATP-binding cassette subfamily A member 3 (ABCA3) that is predominantly expressed in alveolar type II cells, may cause interstitial lung diseases in children (chILD) and adults. Currently, there is no proven therapy, but, frequently, hydroxychloroquine (HCQ) is used empirically. We hypothesized that the in vitro responsiveness to HCQ might correlate to patients' clinical outcomes from receiving HCQ therapy. The clinical data of the subjects with chILD due to ABCA3 deficiency and treated with HCQ were retrieved from the literature and the Kids Lung Register data base. The in vitro experiments were conducted on wild type (WT) and 16 mutant ABCA3-HA-transfected A549 cells. The responses of the functional read out were assessed as the extent of deviation from the untreated WT. With HCQ treatment, 19 patients had improved or unchanged respiratory conditions, and 20 had respiratory deteriorations, 5 of whom transiently improved then deteriorated. The in vitro ABCA3 functional assays identified two variants with complete response, five with partial response, and nine with no response to HCQ. The variant-specific HCQ effects in vivo closely correlated to the in vitro data. An ABCA3⁺ vesicle volume above 60% of the WT volume was linked to responsiveness to HCQ; the HCQ treatment response was concentration dependent and differed for variants in vitro. We generated evidence for an ABCA3 variant-dependent impact of the HCQ in vitro. This may also apply for HCQ treatment in vivo, as supported by the retrospective and uncontrolled data from the treatment of chILD due to ABCA3 deficiency.

Hydroxychloroquine, a successful treatment for lung disease in ABCA3 deficiency gene mutation: a case report

Background

Pulmonary surfactant is a complex mixture of lipids and specific proteins that stabilizes the alveoli at the end of expiration. Mutations in the gene coding for the triphosphate binding cassette transporter A3 (ABCA3), which facilitates the transfer of lipids to lamellar bodies, constitute the most frequent genetic cause of severe neonatal respiratory distress syndrome and chronic interstitial lung disease in children. Hydroxychloroquine can be used as an effective treatment for this rare severe condition.

Case presentation

We report a late preterm Bosnian baby boy (36 weeks) who suffered from a severe form of respiratory distress syndrome with poor response to intensive conventional management and whole exome sequencing revealed homozygous ABCA3 mis-sense mutation. The baby showed remarkable improvement of the respiratory condition after the initiation of Hydroxychloroquine, Azithromycin and Corticosteroids with the continuation of Hydroxychloroquine as a monotherapy till after discharge from the hospital.

Conclusion

Outcome in patients with ABCA3 mutations is variable ranging from severe irreversible respiratory failure in early infancy to chronic interstitial lung disease in childhood (ChILD) usually with the need for lung transplantation in many patients surviving this rare disorder. Hydroxychloroquine through its anti-inflammatory effects or alteration of intra-cellular metabolism may have an effect in treating cases of ABCA3 gene mutations.

[Dyspnea and ventilator dependence after birth in a full-term female infant]

A female infant, aged 43 days, had shortness of breath, cyanosis, groan, and dyspnea since birth. Physical examination showed cyanosis of lips and three-concave sign, and multiple lung imaging examinations showed diffuse ground-glass opacities in both lungs. The girl was given anti-infective therapy and continuous mechanical ventilation but there were no significant improvements in symptoms. Gene testing confirmed a compound heterozygous mutation, c.1890C>A(p.Tyr630Ter)+c.3208G>A(p.Ala1070Thr), in the ABCA3 gene, with the former from her father and the latter from her mother. Pathological examination of the lungs indicated pulmonary interstitial disease. The girl was diagnosed with infantile diffuse pulmonary interstitial disease caused by mutations in the ABCA3 gene. When full-term neonates experience shortness of breath and dyspnea after birth, pulmonary imaging suggests diffuse ground-glass changes, and conventional treatment is not effective (ventilator-dependent), congenital pulmonary surfactant metabolism defects needs to be considered. Gene testing, which can provide a basis for early intervention, prognostic evaluation, and genetic counseling, should be performed as early as possible.

[Dyspnea and ventilator dependence after birth in a full-term female infant]

A female infant, aged 43 days, had shortness of breath, cyanosis, groan, and dyspnea since birth. Physical examination showed cyanosis of lips and three-concave sign, and multiple lung imaging examinations showed diffuse ground-glass opacities in both lungs. The girl was given anti-infective therapy and continuous mechanical ventilation but there were no significant improvements in symptoms. Gene testing confirmed a compound heterozygous mutation, c.1890C>A(p.Tyr630Ter)+c.3208G>A(p.Ala1070Thr), in the ABCA3 gene, with the former from her father and the latter from her mother. Pathological examination of the lungs indicated pulmonary interstitial disease. The girl was diagnosed with infantile diffuse pulmonary interstitial disease caused by mutations in the ABCA3 gene. When full-term neonates experience shortness of breath and dyspnea after birth, pulmonary imaging suggests diffuse ground-glass changes, and conventional treatment is not effective (ventilator-dependent), congenital pulmonary surfactant metabolism defects needs to be considered. Gene testing, which can provide a basis for early intervention, prognostic evaluation, and genetic counseling, should be performed as early as possible.