Novel MKRN3 Missense Mutations Associated With Central Precocious Puberty Reveal Distinct Effects on Ubiquitination.

CONTEXT: Loss-of-function mutations in the maternally imprinted genes, MKRN3 and DLK1, are associated with central precocious puberty (CPP). Mutations in MKRN3 are the most common known genetic etiology of CPP. OBJECTIVE: This work aimed to screen patients with CPP for MKRN3 and DLK1 mutations and analyze the effects of identified mutations on protein function in vitro. METHODS: Participants included 84 unrelated children with CPP (79 girls, 5 boys) and, when available, their first-degree relatives. Five academic medical institutions participated. Sanger sequencing of MKRN3 and DLK1 5' upstream flanking and coding regions was performed on DNA extracted from peripheral blood leukocytes. Western blot analysis was performed to assess protein ubiquitination profiles. RESULTS: Eight heterozygous MKRN3 mutations were identified in 9 unrelated girls with CPP. Five are novel missense mutations, 2 were previously identified in patients with CPP, and 1 is a frameshift variant not previously associated with CPP. No pathogenic variants were identified in DLK1. Girls with MKRN3 mutations had an earlier age of initial pubertal signs and higher basal serum luteinizing hormone and follicle-stimulating hormone compared to girls with CPP without MRKN3 mutations. Western blot analysis revealed that compared to wild-type MKRN3, mutations within the RING finger domain reduced ubiquitination whereas the mutations outside this domain increased ubiquitination. CONCLUSION: MKRN3 mutations were present in 10.7% of our CPP cohort, consistent with previous studies. The novel identified mutations in different domains of MKRN3 revealed different patterns of ubiquitination, suggesting distinct molecular mechanisms by which the loss of MRKN3 results in early pubertal onset.

The Insulin-Only Bionic Pancreas Improves Glycemic Control in Non-Hispanic White and Minority Adults and Children With Type 1 Diabetes.

OBJECTIVE: We evaluated the performance of the iLet bionic pancreas (BP) in non-Hispanic White individuals (here referred to as "Whites") and in Black, Hispanic, and other individuals (here collectively referred to as "Minorities"). RESEARCH DESIGN AND METHODS: A multicenter, randomized controlled trial evaluated glycemic management with the BP versus standard of care (SC) in 161 adult and 165 pediatric participants with type 1 diabetes over 13 weeks. RESULTS: In Whites (n = 240), the mean baseline-adjusted difference in 13-week HbA1c between the BP and SC groups was -0.45% (95% CI -0.61 to -0.29 [-4.9 mmol/mol; -6.6 to -3.1]; P < 0.001), while this difference among Minorities (n = 84) was -0.53% (-0.83 to -0.24 [-6.0 mmol/mol; -9.2 to -2.8]; P < 0.001). In Whites, the mean baseline-adjusted difference in time in range between the BP and SC groups was 10% (95% CI 7-12; P < 0.001) and in Minorities was 14% (10-18; P < 0.001). CONCLUSIONS: The BP improves glycemic control in both Whites and Minorities and offers promise in decreasing health care disparities.

Metformin use in children with obesity and normal glucose tolerance--effects on cardiovascular markers and intrahepatic fat.

OBJECTIVE: To determine if metformin improves markers of inflammation, thrombosis, and intrahepatic fat contents in children with uncomplicated obesity. METHODS: Obese children with normal glucose tolerance but elevated highly sensitive C-reactive protein (hsCRP) and/or fibrinogen concentrations (>2 standard deviations) were randomized to structured diet/exercise or diet/exercise and metformin for 6 months. Blood samples, dual energy X-ray absorptiometry data, and liver magnetic resonance images were obtained. RESULTS: Forty-two of 66 recruited children (7-18 years) completed 6 months. Weight loss was modest but more pronounced in the metformin group (-4.9 +/- 1.0 kg) than in the diet/exercise group (-1.7 +/- 1.1 kg, p<0.03), whereas hsCRP and fibrinogen decreased more in the diet/exercise pubertal group. Baseline intrahepatic fat was high but decreased only in the diet/exercise (not metformin) pubertal group. CONCLUSIONS: Six months of metformin therapy improved weight loss and reduced abdominal adiposity, but did not enhance the beneficial effect of diet and exercise on markers related to inflammation, thrombosis, or hepatic fat in obese children with normal glucose tolerance.

Obesity without established comorbidities of the metabolic syndrome is associated with a proinflammatory and prothrombotic state, even before the onset of puberty in children.

BACKGROUND: Metabolic syndrome (MS)-related comorbidities in obesity, such as hypertension, dyslipidemia, and glucose intolerance, are increasingly recognized in children, predisposing them to early cardiovascular disease. OBJECTIVE: The objective of the study was to investigate whether markers of inflammation and prothrombosis are abnormal in obese children without established MS comorbidities across puberty, as compared with lean, age-matched controls. SUBJECTS AND METHODS: Obese children (body mass index >95%) with normal fasting glucose, blood pressure, cholesterol and triglycerides were recruited; lean controls (body mass index 10-75%) had no first-degree relatives with MS. High-sensitivity C-reactive protein (hsCRP), IL-6, plasminogen activator inhibitor 1, and fibrinogen concentrations were measured. Body composition was assessed by waist circumference and dual-energy x-ray absorptiometry. RESULTS: Of 623 children screened, 203 enrolled (106 males, 97 females), aged 7-18 yr, 115 obese, 88 lean (balanced for age and gender), 99 prepubertal, and 104 pubertal. Many screen failures were due to silent comorbidities. Obese subjects with insulin resistance but without MS comorbidities had about 10 times higher hsCRP concentrations than controls and higher fibrinogen, IL-6, and plasminogen activator inhibitor-1 (P < 0.01 all). Differences were significant, even in the prepubertal cohort. hsCRP and fibrinogen correlated with waist circumference (r = 0.73 and 0.40, respectively) and percent fat mass (r = 0.76 and 0.47) (P < 0.0001). CONCLUSION: Childhood obesity per se is associated with a proinflammatory and prothrombotic state before other comorbidities of the MS are present and even before the onset of puberty. Whether biomarkers like hsCRP and fibrinogen are useful in assessing cardiovascular risk and whether these abnormalities are reversible with earlier therapeutic interventions in very young obese children requires further study.