SFTPD and interstitial lung disease: Although the current study prides a diagnostic pilot seed, further studies should be carried out on a larger scale of Egyptian cases with symptoms of interstitial lung disease (ILD) to investigate all surfactant dysfunction causative genes (SFTPA1, SFTPA2, SFTPB, SFTPD, ABCA3, TERT, TERC, TINF2, PARN, NAF1, and MUC5B) by performing NGS-customized panel or whole-exome sequencing techniques.