XDH and urolithiasis: Taken together with the general history of the region and the present day dispersion of the Turkmens and Arabs (see details in Supporting Information) these findings strongly suggest a wide dispersion of the XDH gene c.2164A>T variant in a region prone to urolithiasis, the Afro‐Asian stone‐forming belt.5 Our finding contributes to the view that hereditary xanthinuria might be not such a rare disease.3, 32, 33