The S141L mutation found in the highly conserved serine 141 resulted in impaired trafficking of TRPM6 to the membrane,10, 18 while the P1017R mutation located in the putative pore-forming region is the only known example of a mutation affecting TRPM6-gating properties without altering assembly or trafficking events.19 The remaining three-point mutations were found in three Polish families; however, the authors did not report whether HSH was a consequence of either TRPM6 trafficking or functional impairment.20 Overall, 34 different mutations have been previously described, from which only five are point mutations, thus ∼85% of mutations are truncating. This study contributes five previously unknown missense mutations in the TRPM6 gene leading to HSH. Our patients phenotype showing manifestation in infancy, severe hypomagnesemia at initial presentation with accompanying hypoparathyroidism and hypocalcemia and the mostly subnormal serum Mg2+ levels under oral Mg2+ supplementation are in accordance with previous publications. Likewise, the dosage of daily oral Mg2+ is in the range as that of previously reported