SLC34A2 gene compound heterozygous mutation identification in a patient with pulmonary alveolar microlithiasis and computational 3D protein structure prediction.

We recently diagnosed a patient with pulmonary alveolar microlithiasis (PAM). Because loss-of-function mutations of the SLC34A2 gene are responsible for the development of PAM, we sought to sequence the SLC34A2 gene of the patient and his direct relatives, with a purpose to identify mutations that caused the PAM of the patient as well as the carriers of his family. We found a novel compound heterozygous mutation of the SLC34A2 gene in this patient, which were the mutations of c.1363T > C (p. Y455H) in exon 12 and c.910A > T (p. K304X) in exon 8. Computational prediction of three-dimensional (3D) structures of the mutants revealed that the Y455H mutation resulted in a formation of irregular coils in the trans-membrane domain and the K304X mutation resulted in protein truncation. Our study suggested that sequencing of the SLC34A2 gene together with a computational prediction of the 3D structures of the mutated proteins may be useful in PAM diagnosis and prognosis.