PHKA2 and hyperinsulinemic hypoglycemia, familial, 4: There are two types of PhK deficiency: liver PhK deficiency, which typically manifests in early childhood with symptoms such as hepatomegaly, growth restriction, hypoglycemia and occasionally fasting ketosis; and muscle PhK deficiency, a less common form characterized by myalgia, muscle cramps, exercise intolerance, and progressive muscle weakness [2].