Therefore, by combining AS2 methylation levels, which can be inferred from those measured by the MS-MLPA 320 probe, with those at the conventionally analyzed DMRs, patients with PHP1B can be categorized to reflect the location of cis-regulatory defects affecting the GNAS locus (Figure 6). The gene discussed is GNAS; the disease is pseudohypoparathyroidism type 1B.