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Abstract Objective Idiopathic infantile hypercalcemia (IIH) is a rare disorder of PTH-independent hypercalcemia. CYP24A1 and SLC34A1 gene mutations cause two forms of hereditary IIH. In this study, the clinical manifestations and molecular aspects of six new Chinese patients were investigated. Methods The clinical manifestations and laboratory study of six patients with idiopathic infantile hypercalcemia were analyzed retrospectively. Results Five of the patients were diagnosed with hypercalcemia, hypercalciuria, and bilateral medullary nephrocalcinosis. Their clinical symptoms and biochemical abnormalities improved after treatment. One patient presented at age 11 years old with arterial hypertension, hypercalciuria and nephrocalcinosis, but normal serum calcium. Gene analysis showed that two patients had compound heterozygous mutations of CYP24A1, one patient had a monoallelic CYP24A1 variant, and three patients had a monoallelic SLC34A1 variant. Four novel CYP24A1 variants (c.116G > C, c.287T > A, c.476G > A and c.1349T > C) and three novel SLC34A1 variants (c.1322 A > G, c.1697_1698insT and c.1726T > C) were found in these patients. Conclusions A monoallelic variant of CYP24A1 or SLC34A1 gene contributes to symptomatic hypercalcemia, hypercalciuria and nephrocalcinosis. Manifestations of IIH vary with onset age. Hypercalcemia may not necessarily present after infancy and IIH should be considered in patients with nephrolithiasis either in older children or adults.

Abstract Background To evaluate the efficacy of GH in improving FAH in ISS children in a multicenter study. Methods A real-world observation was carried out. Children with ISS in seven hospitals in China were enrolled. The height gains standard deviation score and the height gain over the target height were evaluated. Results There were 344 ISS patients (217 boys and 127 girls). The baseline average age of boys and girls was 12.7 and 11.7 years, with bone age of 11.7 and 10.1 years, respectively. The baseline height SDS of boys and girls was − 3.07 and − 2.74, and the FAH SDS was − 1.91 and − 1.38, respectively. Compared with the baseline height SDS, the FAH SDS was significantly increased in both boys and girls (both P = 0.0000). The FAH SDS was the highest (gain by 1.54 SD) in the ≥2y treatment course group. Two hundred eighteen patients (218/344, 63.4%) had a FAH SDS > − 2 SD. Among these patients, girls in the 1-2y treatment course group and ≥ 2y group had a FAH SDS higher than TH SDS. Even in the control group, a spontaneous catch-up growth of 1.16 SD was observed. A multivariate linear regression model was used to analyze the results, with FAH SDS as the dependent variable. It was found that the treatment course and baseline height SDS in the boys’ model were statistically significant (P