Two recent works have also reported anomalies in DRC1 as a cause for PCD in men with multiple morphological abnormalities of the sperm flagella (MMAF) [46, 47], but so far, no female cases of infertility were associated with DRC1. Given the DRC1 proposed role and the fact that both twins present the same null variant in the DRC1 gene, we propose that this variant is the cause of PCD and infertility in the twins. The gene discussed is DRC1; the disease is primary ciliary dyskinesia.