We therefore explored our NIPAL1 findings further by testing family members within the 2 families with NIPAL1 variants for total serum magnesium levels, and by evaluating the association between total serum magnesium levels and sporadic NPC using routinely available pre-treatment magnesium testing results from NPC cases and non-cases attending the ENT clinic at the National Taiwan University Hospital. Here, NIPAL1 is linked to nasopharyngeal carcinoma.