This is evidenced by some of these pathologies being associated with protein deficiency or enzymatically inactivating mutations such as immunodeficiency in the case of adenosine deaminase deficiency [1], myopathies for TK2-deficiency [2], hemolytic anemia in NT5C3A-mutated patients [3], and a more complex clinical presentation for hCNT1-deficiency [4]. Here, TK2 is linked to hyperinsulinemic hypoglycemia, familial, 4.