English Springer Spaniel, American Cocker Spaniels, Whippet and mixed breed dogs with PFK-M deficiency due to a nonsense mutation in the Pfkm gene (c.2228A>G in exon 21; p.Trp743*) have been identified [217,218,219,220,221,222]. Here, PFKM is linked to hyperinsulinemic hypoglycemia, familial, 4.