Additional expression profiling of miR-6891-5p and both IGHA1 and IGHA2 transcripts within a cohort of B-lymphoblastoid cell lines (B-LCLs) obtained from patients with selective IgA deficiency and unaffected family members reveals a significant increase in miR-6891-5p expression and an attenuation of IGHA1 and IGHA2 expression among affected individuals. Here, IGHA1 is linked to selective IgA deficiency disease.