A compound heterozygous combination of SLC34A2 variants in pulmonary alveolar microlithiasis: A case report and literature review

Abstract

Pulmonary Alveolar Microlithiasis (PAM) is a rare hereditary lung disorder characterized by the intra-alveolar deposition of calcium phosphate microliths. It is primarily familial and follows an autosomal recessive inheritance pattern, with no significant gender disparity in incidence. In its early stages, PAM is often asymptomatic, and most cases are detected incidentally through abnormal imaging findings during routine health examinations. We report a case of a male patient in his mid-50 s with a 10-year history of exertional dyspnea and cough unresponsive to conventional therapy. Initially diagnosed and treated for emphysema in early 2024, the patient was readmitted two months later with progressive dyspnea and cyanosis. The diagnosis of PAM was confirmed by typical medical imaging and pathological examination. Genetic analysis identified a previously unreported compound heterozygous combination of SLC34A2 variants: a c.910A > T (p.Lys304*) nonsense variant in exon 8 and a heterozygous ∼5.5 kb copy-number deletion at 4p15.2 (encompassing exons 2–6), thereby expanding the catalogue of reported PAM-associated genetic combinations. No recurrence was observed during one-year follow-up after bilateral lung transplantation.