Surfactant Metabolism Dysfunction, Pulmonary, 3

Alternative Names

  • SMDP3
  • Pulmonary Alveolar Proteinosis, Congenital, 3
  • Interstitial Lung Disease due to ABCA3 Deficiency
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Congenital malformations of the respiratory system

OMIM Number

610921

Mode of Inheritance

Autosomal recessive

Gene Map Locus

16p13.3

Description

Surfactant metabolism dysfunction, pulmonary, 3 (SMDP3) is an autosomal recessive disorder characterized by failure to thrive, severe respiratory distress, tachypnea and surfactant deficiency.  The initial clinical presentation is usually severe, and starts during the first year of life.  However, onset of the condition may sometimes be delayed and the presentation may be later in infancy or childhood. 

Diagnosis of the condition is done through chest radiography that shows granular, hazy, ground-glass interstitial opacifications in patients’ lungs.  Most infants affected with the severe form of the disease die within the first months of life.  However, patients with the milder form of the condition can survive into childhood, adolescence or even adulthood.  The only curative treatment available is a lung transplant. 

Molecular Genetics

Mutations in the ABCA3 gene cause SMDP3.  The encoded protein is expressed in alveolar type II pneumocytes and located in the limiting membrane of lamellar bodies.  It is critical for the synthesis of surfactants that help in reducing the surface tension of alveolar tissue and preventing lung collapse.

More than 200 mutations in the ABCA3 gene have been implicated in the development of interstitial lung disease. 

Epidemiology in the Arab World

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Other Reports

Saudi Arabia

Mukhtar et al, (2016) described three children of consanguineous Saudi couples belonging to an extended family that presented with respiratory distress and failure to thrive.  The first patient was a girl and her chest CT scan showed nonspecific diffuse ground glass opacities bilaterally.  The option of lung transplant was discussed with her parents, but she was lost to follow-up.  Her brother had respiratory symptoms since birth and died at age of 42-days. The second patient was her 7-month old female cousin.  Few hours after birth, she developed respiratory distress with tachypnea and cyanosis, requiring oxygen therapy.  Her chest CT scan showed evidence of ground glass opacities involving both lungs.  She had a successful lung transplant performed the age of 1-year and 6-months.  The third patient was another cousin of the first patient.  She had respiratory distress with progressive deterioration, which required mechanical ventilation.  Her chest CT scan was in line with the previous presentations seen in the other two patients.  She died at the age of 6-months. Mukhtar et al., (2016) identified a homozygous mutation in the ABCA3 gene.  

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