SLC26A2 and hyperinsulinemic hypoglycemia, familial, 4: The S-deficiency responsive genes considered are the following sulfate transporter genes: SULTR 1;1 (sulfate transporter 1;1), SULTR 1;2 (sulfate transporter 1;2), SULTR 1;3 (sulfate transporter 1;3), SULTR 2;1 (sulfate transporter 2;1), SULTR 2;2 (sulfate transporter 2;2) and sulfur assimilation key enzyme genes: APR1 (APS reductase 1), and APR2 (APS reductase 2) (Figure 3).