Idiopathic infantile hypercalcemia (IIH) is characterized by severe hypercalcemia with failure to thrive, vomiting, dehydration, and nephrocalcinosis. Recently, mutations in the vitamin D catabolizing enzyme 25-hydroxyvitamin D 3 -24-hydroxylase (CYP24A1) were described that lead to increased sensitivity to vitamin D due to accumulation of the active metabolite 1,25-(OH) 2 D 3 . In a subgroup of patients who presented in early infancy with renal phosphate wasting and symptomatic hypercalcemia, mutations in CYP24A1 were excluded. Four patients from families with parental consanguinity were subjected to homozygosity mapping that identified a second IIH gene locus on chromosome 5q35 with a maximum logarithm of odds (LOD) score of 6.79. The sequence analysis of the most promising candidate gene, SLC34A1 encoding renal sodium-phosphate cotransporter 2A (NaPi-IIa), revealed autosomal-recessive mutations in the four index cases and in 12 patients with sporadic IIH. Functional studies of mutant NaPi-IIa in Xenopus oocytes and opossum kidney (OK) cells demonstrated disturbed trafficking to the plasma membrane and loss of phosphate transport activity. Analysis of calcium and phosphate metabolism in Slc34a1-knockout mice highlighted the effect of phosphate depletion and fibroblast growth factor-23 suppression on the development of the IIH phenotype. The human and mice data together demonstrate that primary renal phosphate wasting caused by defective NaPi-IIa function induces inappropriate production of 1,25-(OH) 2 D 3 with subsequent symptomatic hypercalcemia. Clinical and laboratory findings persist despite cessation of vitamin D prophylaxis but rapidly respond to phosphate supplementation. Therefore, early differentiation between SLC34A1 (NaPi-IIa) and CYP24A1 (24-hydroxylase) defects appears critical for targeted therapy in patients with IIH.
Aims/hypothesis Diabetes is one of the cardinal features of thiamine-responsive megaloblastic anaemia (TRMA) syndrome. Current knowledge of this rare monogenic diabetes subtype is limited. We investigated the genotype, phenotype and response to thiamine (vitamin B 1 ) in a cohort of individuals with TRMA-related diabetes. Methods We studied 32 individuals with biallelic SLC19A2 mutations identified by Sanger or next generation sequencing. Clinical details were collected through a follow-up questionnaire.Results We identified 24 different mutations, of which nine are novel. The onset of the first TRMA symptom ranged from birth to 4 years (median 6 months [interquartile range, IQR 3-24]) and median age at diabetes onset was 10 months . At presentation, three individuals had isolated diabetes and 12 had asymptomatic hyperglycaemia. Followup data was available for 15 individuals treated with thiamine for a median 4.7 years (IQR 3-10). Four patients were able to stop insulin and seven achieved better glycaemic control on lower insulin doses. These 11 patients were significantly younger at diabetes diagnosis (p = 0.042), at genetic testing (p = 0.01) and when starting thiamine (p = 0.007) compared with the rest of the cohort. All patients treated with thiamine became transfusion-independent and A list of the members of the International Neonatal Diabetes Consortium is included in the electronic supplementary material (ESM).Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00125-018-4554-x) contains peer-reviewed but unedited supplementary material, which is available to authorised users.
Background CANDLE syndrome (an acronym for Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated Temperature) is a recently described rare autosomal recessive disorder charaterized by systemic autoinflammation. Clinical manifestations include presentation in the first year of life, episodes of fever accompanied by erythematous skin lesions, progressive lipodystrophy, violaceous periorbital swelling and failure to thrive. This syndrome is caused by loss of function mutations and malfunction of the immunoproteasome complex. Most patients have biallelic mutations in the PSMB8 gene that encodes the β5i catalytic subunit of the immunoproteasome. Examples of digenic inheritance have been also described in CANDLE. CANDLE patients have strong type I interferon gene expression signature and they are responsive to treatment with JAK inhibitors. However, possible serious side-effects remain a concern. Here, we report another patient with CANDLE whose disease activity was well controlled by the treatment with baricitinib. Case presentation We report a Bulgarian patient of the Turkish ancestry who carries biallelic mutations in the PSMB8 gene: p.Ala92Val and p.Lys105Gln. The pathogenic variant p.Ala92Val has not been previously described in patients with CANDLE. We also comment on the unusual feature in this patient, nephrolithiasis, that has not been described in other patients, however it might be related to the positive family history for kidney stones. We have treated the patient with the JAK inhibitor baricitinib for the past year and we observed a significant amelioration of his inflammatory episodes, skin and joint manifestations, and improvements in physical activities and growth. The treatment with glucocorticoids (GC) was completely discontinued. No side effects have been observed, however they remain in consideration for a life-long therapy of this disease. Conclusions CANDLE should be suspected in patients with early-onset systemic inflammatory disease and prominent skin manifestations. Molecular testing can confirm the clinical diagnosis and is very important in guiding therapies. Treatment with JAK inhibitors is highly efficacious and appears to be safe in children with CANDLE and other intereforonopathies.
View related articles View Crossmark data Citing articles: 4 View citing articles ARTICLE; MEDICAL BIOTECHNOLOGY Glycemic control in type 1 diabetes mellitus among Bulgarian children and adolescents: the results from the first and the second national examination of HbA 1c
Achievement of optimal glycaemic control in children and adolescents with type 1 diabetes depends on the knowledge of the patients and their parents about the control of the disease and the family support. The aim of this study was to investigate the importance of the social standard of the families determined by the employment of the parents and their educational qualification on the control of diabetes. Two consecutive national multi-centre cross-sectional studies of patients with type 1 diabetes, aged 0-19 years, for HbA 1c were conducted in 2012 and in 2014. The first study included 829 patients (422 boys, 407 girls), and the second -498 patients; 281 patients participated in both studies. The patients whose parents are with primary education showed the highest level of HbA 1c in both studies: 9.73% § 2.38% and 9.27% § 1.54% in the first, and the second study, respectively. The patients whose parents have university education achieved the best control: HbA 1c is 8.45% § 1.76% and 7.84% § 1.24%, respectively. The cohorts of diabetic patients whose parents have secondary (p = 0.035) and university education (p < 0.001) showed significant reduction of HbA 1c in the second study compared to the first one. The patients in families with unemployed parents or families in which only the mother is employed showed the highest levels of HbA 1c . Our results underline the importance of the educational qualification and the social standard of the family for the proper control of this chronic disease.
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