CYP24A1 and SLC34A1 Pathogenic Variants Are Uncommon in a Canadian Cohort of Children with Hypercalcemia or Hypercalciuria.

OBJECTIVES: Biallelic pathogenic variants in CYPA24A1 and SLC34A1 are causes of idiopathic infantile hypercalcemia. Pathogenic variants in both may also give rise to hypercalciuria with nephrocalcinosis or nephrolithiasis without previous hypercalcemia (renal group). Our objective was to examine the frequency of CYP24A1 or SLC34A1 variants in children with early hypercalcemia or late-onset hypercalciuria. METHOD: Forty-one children from 7 centers across Canada were recruited. Local investigations were undertaken. The serum was evaluated by liquid chromatography tandem-mass spectrometry for the ratio of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3, (25-OH-D3:24,25-(OH)2D3), an elevation pathognomonic for the loss of function of the CYP24A1 enzyme. Mutational analyses were undertaken. Family cascade screening was performed if pathogenic variants were detected in probands. RESULTS: Twenty-nine children had early-onset hypercalcemia; none had elevated 25-OH-D3:24,25-(OH)2D3 or variants. Interestingly, 2 of 12 in the renal group had elevated 25-OH-D3:24,25-(OH)2D3 and presented as preadolescents. In case 1, cascade testing revealed a sibling and parent with asymptomatic pathogenic variants in CYP24A1. Four CYP24A1 pathogenic variants were identified in these 2 probands: 3 have been described in European populations, and 1 is a rare variant in exon 7 (c931delC) that is likely pathogenic. No SLC34A1 pathogenic variants were detected. CONCLUSION: In Canada, pathogenic variants in CYP24A1 appear to manifest with late-onset hypercalciuria and its sequelae. The 25-OH-D3:24,25-(OH)2D3 ratio is an excellent tool for screening for biallelic pathogenic variants in CYP24A1. We confirm that cascade testing is important for these variants.

Risk of adrenal insufficiency following intra-articular or periarticular corticosteroid injections among children with chronic arthritis.

Objectives Intra-articular and/or periarticular corticosteroid injection (IACI) is a common procedure in pediatric rheumatology. Despite many adult studies demonstrating a significant risk of adrenal insufficiency (AI) following the procedure, very little evidence is available in the pediatric literature regarding this risk. The main goal of this study is to evaluate the prevalence of AI in children with chronic arthritis following IACI. Methods This is a retrospective study including children aged 0-18 years who had an IACI from June 2017 to July 2019. An 8:00 morning cortisol (8MC) sample was drawn around two weeks after the injection, and an ACTH 1mcg stimulation test was performed if morning cortisol level was low. AI was defined as an 8MC under 50 nmol/L or an abnormal ACTH stimulation test. Risks factors for AI and its duration were assessed. Results Sixty patients were included in this study. AI prevalence was 30% with 18 of 60 affected patients. The corticosteroid dose injected was statistically associated with the development of AI. Median duration of AI was 181 days for the nine patients who were followed up until resolution of AI. Four patients developed symptoms of AI, namely fatigue (2 of 4), nausea (2 of 4) and abdominal pain (3 of 4). None were hospitalized or died. Conclusions In this cohort of children with chronic arthritis who had an IACI, we found a high prevalence of AI. Monitoring and counseling of such complication is warranted until further evidence is available.

Sleep and quality of life of patients with glycogen storage disease on standard and modified uncooked cornstarch.

BACKGROUND: Glycemic control in hepatic glycogen storage diseases (GSDs) relies on specific nutritional recommendations, including strict avoidance of a fasting period. Uncooked cornstarch (UCCS) is an important therapeutic component. A new modified UCCS, Glycosade™, was created with the objective of prolonging euglycemia. We aimed to determine the length of euglycemia on Glycosade™ using a continuous glucose monitor (CGM) and to evaluate whether longer euglycemia and thus less nighttime interruptions would improve sleep and quality of life (QoL) after the introduction of the modified cornstarch. METHODS: We conducted a prospective cohort study to assess quality and quantity of sleep and quality of life (QoL) in patients with GSDs on standard UCCS and after the introduction of Glycosade™. Sleep and QoL evaluation was done for patients using validated questionnaires, a standardized sleep diary and actigraphy. Length of fast and glucose variability were determined with CGM. RESULTS: Nine adults with GSD Ia took part in the study. Glycosade™ introduction was done under close supervision during a hospital admission. Comparison of sleep in 9 patients showed sleep disturbances on standard UCCS that were improved with Glycosade™. QoL was normal both pre and post Glycosade™. The CGM confirmed maintenance of a longer fasting period with Glycosade™ at home. CONCLUSION: Glycosade™ represents an alternative option for GSD patients. We showed possible benefits in terms of sleep quality. We also confirmed the longer length of fast on Glycosade™. SYNOPSIS: A new modified form of uncooked starch for patients with glycogen storage disease represents an alternative option as it showed a longer length of fast and improvements in sleep quality.

A founder AGL mutation causing glycogen storage disease type IIIa in Inuit identified through whole-exome sequencing: a case series.

BACKGROUND: Glycogen storage disease type III is caused by mutations in both alleles of the AGL gene, which leads to reduced activity of glycogen-debranching enzyme. The clinical picture encompasses hypoglycemia, with glycogen accumulation leading to hepatomegaly and muscle involvement (skeletal and cardiac). We sought to identify the genetic cause of this disease within the Inuit community of Nunavik, in whom previous DNA sequencing had not identified such mutations. METHODS: Five Inuit children with a clinical and biochemical diagnosis of glycogen storage disease type IIIa were recruited to undergo genetic testing: 2 underwent whole-exome sequencing and all 5 underwent Sanger sequencing to confirm the identified mutation. Selected DNA regions near the AGL gene were also sequenced to identify a potential founder effect in the community. In addition, control samples from 4 adults of European descent and 7 family members of the affected children were analyzed for the specific mutation by Sanger sequencing. RESULTS: We identified a homozygous frame-shift deletion, c.4456delT, in exon 33 of the AGL gene in 2 children by whole-exome sequencing. Confirmation by Sanger sequencing showed the same mutation in all 5 patients, and 5 family members were found to be carriers. With the identification of this mutation in 5 probands, the estimated prevalence of genetically confirmed glycogen storage disease type IIIa in this region is among the highest worldwide (1:2500). Despite identical mutations, we saw variations in clinical features of the disease. INTERPRETATION: Our detection of a homozygous frameshift mutation in 5 Inuit children determines the cause of glycogen storage disease type IIIa and confirms a founder effect.

Hypothalamic hamartoma associated with central precocious puberty and growth hormone deficiency.

Hypothalamic hamartomas (HHs) are tumors generally associated with isolated central precocious puberty (CPP). To our knowledge, we report a unique case of a girl with HH associated with CPP and growth hormone deficiency. This case highlights the complex interaction between HHs and the hypothalamic-pituitary-gonadal axis. It also emphasizes the value of close follow-up of growth velocity in these patients even after treatment of the CPP.

Long-term bone health in glucocorticoid-treated children with rheumatic diseases.

Glucocorticoids (GC) are a standard treatment for pediatric rheumatic disease. Recent literature highlights skeletal vulnerability in children with rheumatic illness, including vertebral and peripheral fractures and reductions in bone mineral density in longitudinal follow-up. Annual vertebral fracture incidence of 4-6 % in those recently diagnosed and prevalence of 7-28 % in those several years post diagnosis have been reported. The fractures are often asymptomatic, often thoracic in location, and usually of mild, anterior wedge morphology. Diseases with more systemic involvement and severe inflammation (SLE, JDM) seem to be at higher risk. Neither BMD nor GC dose are ideal predictors for risk of fractures. These children also seem to have an increased incidence of long-bone fractures, particularly in the forearm and wrist; in the scant literature, long-bone fractures are not predictive of vertebral fractures. Bone mass accrual is typically suboptimum across time, although the use of potent steroid-sparing anti-inflammatory agents may counteract the effects of GC and active disease. Vitamin D insufficiency warrants ongoing monitoring. Additional targeted studies are justified to increase understanding of bone health risks in this population.