A novel homozygous frameshift mutation in exon 13 of SLC34A2 gene causing pulmonary alveolar microlithiasis: A case report.

Background: Pulmonary Alveolar Microlithiasis (PAM) is an extremely rare, progressive, and irreversible lung disease characterized by diffuse deposition of calcium phosphate microliths in alveoli. Most cases present with nonspecific symptoms or are asymptomatic, making diagnosis challenging. Methods: We present the case of a 32-year-old male carpenter who was a 15-year smoking and drinking history and admitted due to bilateral lung lesions detected during physical examination, accompanied by intermittent chest tightness, cough and expectoration. Report the clinical manifestations, imaging findings, and analysis of SLC34A2 gene amplification and sequencing results to elucidate the mutation phenotype in this case. Results: Chest CT showed "blizzard-like" diffuse calcified nodules, and genetic testing identified a novel homozygous frameshift deletion mutation c.1903delG (p.C635Afs*34) in exon 13 of the SLC34A2 gene. The diagnosis was highly suggestive of PAM. Conclusion: This case presents a novel pathogenic mutation of SLC34A2 not previously reported, enriching the mutation spectrum of PAM. The high resolution CT combined with genetic testing is emphasized in the diagnosis of PAM.