A novel compound heterozygous mutation in the SLC34A2 gene causes pulmonary alveolar microlithiasis

A 36-year-old female patient was admitted to the hospital in July 2022 with a 7-month history of dyspnea and chest distress. Her blood oxygen saturation was measured at 98% without oxygen therapy. Physical examination and laboratory tests did not reveal any significant abnormalities. Pulmonary function tests showed no impairment in spirometry and diffusion capacity. High- resolution computed tomography (HRCT) of the chest showed extensive micronodular opacity, pleural calcification, signs of fibrosis and interstitial thickening in the lung (Figure 1). Histopathological examination of the biopsied lung tissue showed round, concentrically laminated microliths occupying the alveoli accompanied by thickened, fibrotic interstitium (Figure 2). The final diagnosis was pulmonary alveolar microlithiasis (PAM) based on the typical radiographic and pathology findings. Genetic analysis by whole-exome sequencing of the patient identified a novel compound heterozygous mutation in the SLC34A2 gene, which were the mutations of c.1267G>A(p. Gly423Arg)in exon 11 and c.910A>T(p.Lys304 )in exon 8. Further analysis by Sanger sequencing of the parents’ DNA confirmed that they were both heterozygous carriers (Figure 3). Incidentally, her parents are not consanguineous. None of them complained of discomfort and their HRCT of the chest scans were normal. Currently, there is no effective treatment for PAM except for lung transplantation. The patient was advised to continue her follow-up at the pulmonary clinic, and lung transplantation will be considered if right heart failure or severe refractory hypoxemia occurs. © The Author(s) 2023. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved.