Efficacy and pharmacokinetics of betaine in CBS and cblC deficiencies: a cross-over randomized controlled trial.

BACKGROUND: Betaine is an "alternate" methyl donor for homocysteine remethylation catalyzed by betaine homocysteine methyltransferase (BHMT), an enzyme mainly expressed in the liver and kidney. Betaine has been used for more than 30 years in pyridoxine non-responsive cystathionine beta-synthase (pnrCBS) and cobalamin C (cblC) deficiencies to lower the hyperhomocysteinemia, although little is known about the optimal therapeutic dosage and its pharmacokinetic in these patients. AIMS: We compared 2 betaine doses (100 mg/kg/day vs. 250 mg/kg/day) in children affected by pnrCBS or cblC deficiencies. We also measured the pharmacokinetics parameters after a single dose of betaine (100 or 250 mg/kg) in these patients. METHODS: We conducted a prospective, randomized, crossover clinical trial with blinded evaluation. The primary outcome was the equivalence of total plasma homocysteine (tHcy) concentrations upon one-month oral treatment with betaine at 100 versus 250 mg/kg/day. RESULTS: Eleven patients completed the study (5 pnrCBS and 6 cblC). tHcy concentrations were equivalent after a one-month treatment period for the two betaine dosages. Multivariate analysis showed a significant effect of betaine dose on methionine (Met) (p = 0.01) and S-adenosylmethionine (SAM) concentrations (p = 0.006). CONCLUSIONS: Our analysis shows that there is no overt benefit to increasing betaine dosage higher than 100 mg/kg/day to lower tHcy concentrations in pnrCBS and cblC deficiencies. However, increasing betaine up to 250 mg/kg/d could benefit cblC patients through the increase of methionine and SAM concentrations, as low Met and SAM concentrations are involved in the pathophysiology of this disease. In contrast, in pnrCBS deficiency, betaine doses higher than 100 mg/kg/day could be harmful to these patients with pre-existing hypermethioninemia. TRIAL REGISTRATION: Clinical Trials, NCT02404337. Registered 23 May 2015-prospectively registered, https://clinicaltrials.gov .

Spatiotemporal variation of childhood hyperthyroidism: a 10-year nationwide study.

Objective: Childhood hyperthyroidism is mostly caused by Graves' disease, a rare autoimmune disease in children. Epidemiological data are scarce and the variability of within-region incidence is unknown. We aimed to provide the first description of temporal trends in pediatric hyperthyroidism in France and to explore spatial trends, with a view to identifying possible environmental triggers. Design and methods: We performed an observational population-based study on data collected from the National Health Data System, covering the 2008-2017 period and the whole of France. We identified patients with an indicator reflecting incident cases of treated hyperthyroidism, in children aged 6 months-17.9 years, localized at the scale of the département (equivalent to a county) of residence. We performed descriptive analyses of incidence rate by sex, age, and year, and used a spatiotemporal model for estimation at département level. Results: We identified 4734 incident cases: 3787 girls (80%) and 947 boys (20%). The crude incidence rate was 3.35 (95% CI: 3.26; 3.45) per 100 000 person-years over the study period. We estimated the increase in incidence between 2008 and 2017 at 30.1% (19.0%; 42.3%). Annual incidence rate increased linearly over the 10-year period in both girls and boys, rising similarly in all age groups and in all départements. The spatial model highlighted marked heterogeneity in the risk of childhood hyperthyroidism across France. Conclusion: The trend toward increasing incidence observed may reflect changes in genetic and environmental interactions, and the marked spatial heterogeneity may reflect localized ethnic or environmental factors worthy of further investigation.

X chromosome gene dosage as a determinant of congenital malformations and of age-related comorbidity risk in patients with Turner syndrome, from childhood to early adulthood.

Objective Turner Syndrome is associated with several phenotypic conditions associated with a higher risk of subsequent comorbidity. We aimed to evaluate the prevalence of congenital malformations and the occurrence of age-related comorbid conditions and to determine whether the frequencies of congenital and acquired conditions depend on X chromosome gene dosage, as a function of karyotype subgroup. Design and methods This national retrospective observational cohort study includes 1501 patients. We evaluated the prevalence of congenital malformations and the cumulative incidence of subsequent specific comorbidities at five-year intervals, from the ages of 10 to 30 years, with stratification by karyotype subgroup: 45,X (n = 549), 45,X/46,isoXq (n = 280), 46,X,r(X)/46,XX (n = 106), 45,X/46,XX (n = 221), presence of Y (n = 87). Results Median age was 9.4 (3.7-13.7) years at first evaluation and 16.8 (11.2-21.4) years at last evaluation. Congenital heart (18.9%) malformations were more frequent in 45,X patients, and congenital renal (17.2%) malformations were more frequent in 45,X, 45,X/46,isoXq and 46,X,r(X)/46,XX patients than in those with 45,X/46,XX mosaicism or a Y chromosome (P < 0.0001). The cumulative incidence of subsequent acquired conditions, such as thyroid disease, hearing loss, overweight/obesity, dyslipidemia and, to a lesser extent, celiac disease, glucose intolerance/type 2 diabetes, hypertension and liver dysfunction increased with age, but less markedly for patients with mosaicism than for those with other karyotypes. Patients with a ring chromosome were more prone to metabolic disorders. Conclusion These data suggest that X gene chromosome dosage, particularly for Xp genes, contributes to the risk of developing comorbidities.

Early Determinants of Thyroid Function Outcomes in Children with Congenital Hypothyroidism and a Normally Located Thyroid Gland: A Regional Cohort Study.

BACKGROUND: An increase in the incidence of congenital hypothyroidism (CH) with a normally located gland has been reported worldwide. Affected individuals display transient or permanent CH during follow-up in childhood. This study aimed to determine the prevalence of transient CH and to investigate the possibility of distinguishing between transient and permanent CH in early infancy. METHODS: This observational cohort study included all patients identified by systematic neonatal screening for CH in the northern Parisian region between 2002 and 2012 and treated for CH with a normally sited gland. A standardized data collection form was completed prospectively at diagnosis. Patients were classified during follow-up as having transient or permanent CH. RESULTS: Of the 92 patients initially treated for CH with a normally located gland during the neonatal period, 49 (54%) had a transient form of CH after the cessation of levothyroxine (LT4) treatment at 1.5 (0.6-3.2) years of age. Multivariate analysis revealed that transient CH was associated with a lower likelihood of having a first-degree family history of CH (p = 0.03) and a lower LT4 dose at six months of age (p = 0.03) than permanent CH. Sex, ethnicity, neonatal problems (e.g., prematurity, being small for gestational age, and/or neonatal distress), iodine status, coexisting malformations, initial CH severity, and thyroid morphology at diagnosis had no effect. Receiver operating characteristics curve analysis showed that a cutoff of 3.2 µg/kg/day for LT4 dose requirement at six months of age had a sensitivity of 71% and a specificity of 79% for predicting transient CH, with values below this threshold considered predictive of transient CH. CONCLUSION: In patients with CH and a normally located gland, these findings highlight the need to evaluate LT4 dose requirements early, at six months of age, particularly in patients with no family history of CH, for early identification of the approximately 50% of patients for whom treatment should be stopped.