CTLA4, SH2B3, and CLEC16A diversely affect the progression of early islet autoimmunity in relatives of Type 1 diabetes patients

The HLA region is the major genetic risk determinant of Type 1 diabetes. How non-HLA loci contribute to the genetic risk is incompletely understood, but there are indications that at least some impact progression of asymptomatic autoimmunity. We examined whether SNPs in 7 susceptibility loci (INS, SH2B3, PTPN2, PTPN22, CTLA4, CLEC16A, and IL2RA) could improve prediction of the progression from single to multiple autoantibody positivity, and from there on to diagnosis. SNPs were genotyped in persistently autoantibody positive relatives by allelic discrimination qPCR and disease progression was studied by multivariate Cox regression analysis. In our cohort, only the CTLA4 GA genotype (rs3087243, P = 0.002) and the CLEC16A AA genotype (rs12708716, P = 0.021) were associated with accelerated progression from single to multiple autoantibody positivity, but their effects were restricted to presence of HLA-DQ2/DQ8, and IAA as first autoantibody, respectively. The interaction of CTLA4 and HLA-DQ2/DQ8 overruled the effect of DQ2/DQ8 alone. The HLA-DQ2/DQ8-mediated risk of progression to multiple autoantibodies nearly entirely depended on heterozygosity for CTLA4. The SH2B3 TT genotype (rs3184504) was protective for HLA-DQ8 positive subjects (P = 0.003). At the stage of multiple autoantibodies, only the CTLA4 GA genotype was a minor independent risk factor for progression towards clinical diabetes (P = 0.034). Our study shows that non-HLA polymorphisms impact progression of islet autoimmunity in a subgroup-, stage- and SNP-specific way, suggesting distinct mechanisms. If confirmed, these findings may help refine risk assessment, follow-up, and prevention trials in risk groups.

Efficacy and safety of a 4-year combination therapy of growth hormone and gonadotropin-releasing hormone analogue in pubertal girls with short predicted adult height

OBJECTIVES

To improve adult height in pubertal girls with a poor height prediction, treatment with growth hormone (GH) can be used in combination with a gonadotropin releasing hormone agonist (GnRHa), to delay closure of the growth plates. However, there are few studies to support this practice, and they show conflicting results. The objective of this trial is to assess the safety and efficacy of this combination treatment in early pubertal girls with a short predicted height, in comparison with matched controls.

DESIGN PATIENTS AND METHODS

We designed an open-label, multicenter, interventional case-control study. Early pubertal girls with predicted adult height (PAH) below -2.5 SDS, were recruited in tertiary care centers in Belgium. They were treated for four years with GH and GnRHa. The girls were followed until adult height (AH) was reached. AH vs PAH, AH vs Height at start, and AH vs Target Height (TH) were evaluated, as well as safety parameters. Control data were assembled from historical patient files or from patients who preferred not to participate in the study.

RESULTS

Sixteen girls with mean age ( ± SD) at start of 11.0 years (± 1.3) completed the study protocol and follow-up. Their mean height ( ± SD) increased from 131.3 ± 4.1 cm (-2.3 ± 0.7 SDS) at start of treatment to 159.8 ± 4.7 cm (-1.1 ± 0.7 SDS) at AH. In matched controls, height increased from 132.3 ± 4.2 cm (-2.4 ± 0.5 SDS) to 153.2 ± 3.4 cm (-2.1 ± 0.6 SDS) (p<0.001). AH surpassed initial PAH by 12.0 ± 2.6 cm in treated girls; and by 4.2 ± 3.6 cm in the controls (p<0.001). Most treated girls reached normal adult height (>-2SD) (87.5%) and 68.7% reached or superseded the target height (TH), which was the case in only a minority of the controls (37.5% and 6.2%, respectively) (p= 0.003 and 0.001). A serious adverse event possibly related to the treatment, was a fracture of the metatarsals.

CONCLUSION

A four-year GH/GnRHa treatment in early pubertal girls with a poor PAH seems safe and results in a clinically relevant and statistically significant increase in AH compared with matched historical controls.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT00840944.

Six novel variants in the MKRN3 gene causing central precocious puberty

Context

Idiopathic central precocious puberty (iCPP) is defined by the premature re-activation of the hypothalamic-pituitary-gonadal axis with normal MRI of the central nervous system, causing the development of secondary sexual characteristics prior to the age of 8 years in girls and 9 years in boys. MKRN3 loss of function variants now represent the most common genetic cause of iCPP.

Purpose

To document the clinical course of puberty in 8 families harboring pathogenic MKRN3 variants.

Method

This is an observational case series study of patients with CPP due to MKRN3 variants followed in a single center.

Results

Genetic analysis of MKRN3 was carried out in 28 unrelated patients with iCPP and a family history of paternal inheritance or no/unavailable maternal inheritance, particularly in case of very early and rapidly evolving CPP.

We identified six novel and two recently described variants in the MKRN3 gene in 9 girls, one boy and their family members. These mutations were all predicted to be deleterious by in silico prediction programs

Conclusion

We have identified six novel MKRN3 mutations in children with CPP. An MKRN3 loss of function should be considered after careful history pinpointing paternally inherited CPP. Family segregation study allowed the detection of a MKRN3 variant in two young brothers still prepubertal, raising the question of screening and management of asymptomatic prepubertal family members.

Comparison Between Continuous Versus Flash Glucose Monitoring in Children, Adolescents, and Young Adults with Type 1 Diabetes: An 8-Week Prospective Randomized Trial

INTRODUCTION

To assess the impact of real-time continuous glucose monitoring (RT-CGM) instead of first-generation flash glucose monitoring (FGM) on hypoglycaemia in children and adolescents with type 1 diabetes.

METHODS

In this randomized controlled interventional study, young individuals with type 1 diabetes used RT-CGM or FGM for 8 weeks. We evaluated changes in time below range (TBR), severe hypoglycaemia (SH), HbA1c, glycaemic variability, and impaired awareness of hypoglycaemia with RT-CGM (intervention group) in comparison with FGM.

RESULTS

We randomly assigned 37 participants to either the intervention group (n = 19) or the control group (n = 18). At 8 weeks, we did not find a decrease in TBR in either group, but there was a significant reduction in SH in the intervention group. For participants with TBR ≥ 5% at baseline, we observed significant reductions in 24-h TBR, wake TBR, sleep TBR, and glucose variability at 8 weeks in the intervention group.

CONCLUSIONS

The use of RT-CGM versus FGM decreased SH in young individuals with type 1 diabetes, and TBR and glucose variability in patients with a higher TBR at baseline. The patient's history should be taken into account when advising on the method of blood glucose monitoring, as RT-CGM could be more effective in younger patients at high risk for SH.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04249102.

Genetic variation at ERBB3/IKZF4 and sexual dimorphism in epitope spreading in single autoantibody-positive relatives

AIMS/HYPOTHESIS

We examined whether the non-HLA susceptibility locus ERBB3/IKZF4 influences progression of type 1 diabetes stage specifically according to sex.

METHODS

SNPs of ERBB3 (rs2292239 T/G) and IKZF4 (rs1701704 G/T) were screened by allelic discrimination quantitative PCR assay in first-degree relatives of type 1 diabetes patients who had developed at least one circulating autoantibody. The effect of ERBB3/IKZF4 genotypes and sex, on the progression of single autoantibody positivity to multiple autoantibody positivity and from multiple autoantibody positivity to diabetes, was studied by Kaplan-Meier analysis and multivariate Cox regression.

RESULTS

In the cohort of autoantibody-positive first-degree relatives, the risk allele frequencies for ERBB3 rs2292239 (T) and IKZF4 rs1701704 (G) were increased. There was a significant male excess at the stage of multiple autoantibody positivity (p = 0.021). In Kaplan-Meier survival analysis, progression from single to multiple antibody positivity was delayed in female participants with genotype ERBB3 GG (p = 0.018, vs ERBB3 TG+TT) or IKZF4 TT (p = 0.023, vs IKZF4 GT+GG), but not in male participants. In multivariate Cox regression models, the interaction effects between female sex and ERBB3 GG (p = 0.012; HR = 0.305 [95% CI 0.120, 0.773]) or between female sex and IKZF4 TT (p = 0.011; HR = 0.329 [95% CI 0.140, 0.777]) emerged as potential determinants of delayed progression to multiple autoantibodies. The progression from multiple autoantibody positivity to type 1 diabetes appeared not to be influenced by ERBB3/IKZF4.

CONCLUSIONS/INTERPRETATION

In siblings and offspring of type 1 diabetes patients, polymorphism in region ERBB3/IKZF4 may affect disease progression at the level of epitope spreading in female individuals. Our findings suggest that interaction between sex and ERBB3/IKZF4 may contribute to the post-pubertal male excess in type 1 diabetes.

Anti-SARS-CoV-2 antibodies in new-onset type 1 diabetes in children during pandemic in Belgium

OBJECTIVES

Questions are emerging concerning the long-term consequences of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, as a possible increase in type 1 diabetes. This study aims to describe the prevalence of anti-SARS-CoV-2 antibodies in children developing type 1 diabetes during this pandemic in Belgium.

METHODS

This observational study included children and adolescents (under 16 years) admitted with new-onset type 1 diabetes. SARS-CoV-2 serology was taken within the first month of diabetes.

RESULTS

Of the 75 participants, anti-SARS-CoV-2 antibodies were positive in 20% of patients. They had an increased bicarbonate and base excess at diagnosis. Overall 29% of patients presented diabetic ketoacidosis at diagnosis and 9% of them were positive for anti-SARS-CoV-2 antibodies. Insulinoma-associated protein 2 antibodies positivity had significantly higher frequencies in children without anti-SARS-CoV-2 antibodies (49 (81%) vs. 5 (33%), p=0.038). Nine (15%) patients, initially seronegative, have developed anti-SARS-CoV-2 antibodies between the two samples (mean time 8 ± 4 weeks).

CONCLUSIONS

The prevalence of anti-SARS-CoV-2 antibodies in children with newly diagnosed type 1 diabetes (20%) is similar to that found in children without diabetes in Belgium, a country severely affected by this pandemic.

The Retina in Patients With Triple A Syndrome: A Window Into Neurodegeneration?

OBJECTIVE

Experimental evidence suggests that the clinical manifestations of Triple A syndrome result from oxidative stress. Several conditions caused by oxidative stress display retinal involvement. Our objective was to assess the retina and optic nerve involvement in children with Triple A syndrome.

METHODS

Eleven patients with genetically proven Triple A syndrome followed-up in our centre were approached for study participation. The main outcome was the measurement of the thicknesses of the different retinal layers by Optical Coherence Tomography (OCT).

RESULTS

9 patients with triple A syndrome had OCT measurements. 7 patients were children and 2 were adults; 4 were females and 5 were males. The 7 paediatric patients had at least two OCT measured at a mean interval of 7.9 months after the first one. The average Retinal Nerve Fibre Layer thickness was 74 ± 10 µm in patients compared to the paediatric reference range of 100 ± 2 µm (p<0.05).

CONCLUSIONS AND RELEVANCE

This is the first study to document retinal layer thicknesses in a series of patients with Triple A syndrome. Nearly all retinal thickness and peripapillary RNFL measurements were very significantly inferior to the reference range in Triple A patients, whatever their age. RNFL thinning was more marked at the temporal part of the optic nerve. OCT being non-invasive, it represents a promising tool to assess the severity of neurodegeneration in patients with Triple A syndrome.

Diabetic ketoacidosis in children newly diagnosed with type 1 diabetes mellitus: Role of demographic, clinical, and biochemical features along with genetic and immunological markers as risk factors. A 20-year experience in a tertiary Belgian center

BACKGROUND

Diabetic ketoacidosis (DKA) is the leading cause of morbidity and mortality in children with type 1 diabetes (T1D). Little is known about the association between genetic and immunological markers and the risk for DKA at onset of T1D. The aim of this study was to create a model foreseeing the onset of DKA in newly diagnosed patients.

METHODS

This retrospective study included 532 T1D children (aged <18 years at diagnosis) recruited in our hospital, from 1995 to 2014. DKA and its severity were defined according to the criteria of ISPAD. Genetic risk categories for developing T1D were defined according to the Belgian Diabetes Registry. Multivariate statistical analyses were applied to investigate risk factors related to DKA at diagnosis.

RESULTS

Overall 42% of patients presented DKA at diagnosis. This study outlined the major risk of DKA at diagnosis for younger children (<3 years) and for those belonging to ethnic minorities. Children carrying neutral genotypes had a 1.5-fold increased risk of DKA at diagnosis than those with susceptible or protective genotypes, a paradoxical observation not previously reported. Only solitary positive IA-2A increased the risk of DKA at diagnosis. The proposed model could help to predict the probability of DKA in 70% of newly diagnosed cases.

CONCLUSIONS

This was the first reported implication of IA-2A positivity and neutral genotypes predisposing to DKA at diagnosis regardless of its severity. Earlier diagnosis through genetic and immunological screening of high-risk children could decrease DKA incidence at diabetes onset.

Flash Glucose Monitoring Accepted in Daily Life of Children and Adolescents with Type 1 Diabetes and Reduction of Severe Hypoglycemia in Real-Life Use

Background: Flash glucose monitoring (FGM) is covered by the Belgian public health insurance for type 1 diabetes since 2016. The objective of this study was to describe the use of FGM and diabetes outcomes in type 1 diabetic children and adolescents 1 year after reimbursement. Methods: All patients had the choice to convert to FGM or to continue with self-monitoring of blood glucose (SMBG). Clinical data were collected at baseline, at the next visit, and after 12 months; glucose profiles at next visit and after 12 months. Regression analyses were performed to identify predictors of FGM acceptance and changes in metabolic control. Results: A total of 334 subjects were included, of whom 278 (83.2%) switched to FGM. They were younger (13.6 vs. 15.2 years; P = 0.012) and performed more SMBG testing at baseline than patients who did not switch (4.3 vs. 4.1 tests daily; P = 0.008). At the end of follow-up, the rate of severe hypoglycemia decreased by 53% in the group of FGM users (P = 0.012) while it remained stable in SMBG users. Median glycated hemoglobin did not change significantly in both groups. Among subjects who switched to FGM, 15.8% reverted to SMBG after a median use of 5.3 months. Adverse events, diabetes duration, and FGM utilization were independent predictors of the risk for reverting. FGM-related adverse events were associated with a fivefold increased risk to revert to SMBG (hazard ratio = 5.12; P < 0.0001). Conclusions: FGM is relatively well accepted and decreases the risk of severe hypoglycemic events in our pediatric population. FGM is more often discontinued in patients experiencing adverse events and with longer diabetes duration.

Criteria for First-Year Growth Response to Growth Hormone Treatment in Prepubertal Children With Growth Hormone Deficiency: Do They Predict Poor Adult Height Outcome?

Objective: Several criteria for first-year growth response (FYGR) to growth hormone (GH) treatment have been proposed. We explored which FYGR criteria predicted best the final height outcome after GH treatment in prepubertal children with GH deficiency (GHD). Design and methods: Height data of 129 GHD children (83 boys) who attained adult height and had been treated with GH for at least 4 consecutive years with at least 1 year before pubertal onset, were retrieved from the Belgian GH Registry. The FYGR parameters were: (1) increase in height (ΔHt) SDS, (2) height velocity (HV) SDS, (3) ΔHV (cm/year), (4) index of responsiveness (IoR) in KIGS prediction models, (5) first-year HV SDS based on the KIGS expected HV curve (HV KIGS SDS), (6) near final adult height (nFAH) prediction after first-year GH treatment. Poor final height outcome (PFHO) criteria were: (1) total ΔHt SDS <1.0, (2) nFAH SDS <-2.0, (3) nFAH minus midparental height SDS <-1.3. ROC curve analyses were performed to define the optimal cut-off for FYGR parameters to predict PFHO. Only ROC curves with an area under the curve (AUC) of more than 70% were further analyzed. Results: Twelve, 22 and 10% of the children had respectively a total ΔHt SDS <1, nFAH SDS <-2, and nFAH minus midparental height SDS <-1.3. The AUC's ranged between 73 and 85%. The highest AUC was found for first-year ΔHt SDS to predict total ΔHt SDS <1, and predicted nFAH SDS to predict nFAH SDS <-2. The currently used FYGR criteria had low specificities and sensitivities to detect PFHO. To obtain a 95% specificity, the cut-off value (and sensitivity) of FYGR parameters were: ΔHt SDS <0.35 (40%), HV SDS <-0.85 (43%), ΔHV <1.3 cm/year (36%), IoR <-1.57 (17%), HV KIGS SDS <-0.83 (40%) to predict total ΔHt SDS <1; predicted nFAH SDS (with GH peak) <-1.94 (25%), predicted nFAH SDS (without GH peak) <-2.02 (25%) to predict nFAH SDS <-2. At these cut-offs, the amount of correctly diagnosed poor final responders equals the amount of false positives. Conclusion: First-year growth response criteria perform poorly as predictors of poor final height outcome after long-term GH treatment in prepubertal GHD children.

Accelerated Progression to Type 1 Diabetes in the Presence of HLA-A*24 and -B*18 Is Restricted to Multiple Islet Autoantibody-Positive Individuals With Distinct HLA-DQ and Autoantibody Risk Profiles

OBJECTIVE

We investigated the effect of HLA class I risk alleles on disease progression in various phases of subclinical islet autoimmunity in first-degree relatives of patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

A registry-based group of siblings/offspring (aged 0-39 years) was monitored from single- to multiple-autoantibody positivity (n = 267) and from multiple-autoantibody positivity to clinical onset (n = 252) according to HLA-DQ, -A*24, -B*18, and -B*39 status. Genetic markers were determined by PCR sequence-specific oligotyping.

RESULTS

Unlike HLA-B*18 or -B*39, HLA-A*24 was associated with delayed progression from single- to multiple-autoantibody positivity (P = 0.009) but not to type 1 diabetes. This occurred independently from older age (P < 0.001) and absence of HLA-DQ2/DQ8 or -DQ8 (P < 0.001 and P = 0.003, respectively), and only in the presence of GAD autoantibodies. In contrast, HLA-A*24 was associated with accelerated progression from multiple-autoantibody positivity to clinical onset (P = 0.006), but its effects were restricted to HLA-DQ8⁺ relatives with IA-2 or zinc transporter 8 autoantibodies (P = 0.002). HLA-B*18, but not -B*39, was also associated with more rapid progression, but only in HLA-DQ2 carriers with double positivity for GAD and insulin autoantibodies (P = 0.004).

CONCLUSIONS

HLA-A*24 predisposes to a delayed antigen spreading of humoral autoimmunity, whereas HLA-A*24 and -B*18 are associated with accelerated progression of advanced subclinical autoimmunity in distinct risk groups. The relation of these alleles to the underlying disease process requires further investigation. Their typing should be relevant for the preparation and interpretation of observational and interventional studies in asymptomatic type 1 diabetes.

Congenital Hypothyroidism: Long-Term Experience with Early and High Levothyroxine Dosage

AIM

To assess the management and outcome of the congenital hypothyroidism (CH) patients followed at our institution since the introduction of systemic neonatal screening for CH.

STUDY DESIGN

The records of 139 CH patients referred to our center between 1978 and 2014 were retrospectively reviewed. Biochemical and imaging data at diagnosis, initial treatment and growth were analyzed.

RESULTS

111 patients had thyroid dysgenesis (64 ectopy, 46 athyreosis and 1 hypoplasia) and 28 patients had a gland in situ (17 dyshormonogenesis/goiter and 11 normal-sized gland). Levothyroxine treatment was initiated at a median age of 11 days with a mean dose of 11.4 µg/kg/day. Compared to those with ectopy, patients with athyreosis had higher thyroid-stimulating hormone (TSH) and lower thyroxine at diagnosis as well as more delayed bone maturation. Between 1978 and 2014, we observed earlier treatment and earlier TSH normalization. Birth auxology was slightly above the mean of the reference population. Growth at 1 and 6 years and school progression at 11 years were similar to those of the reference population.

CONCLUSION

Ectopy is the commonest cause of CH. Children with CH treated early with a mean levothyroxine dose of 11.4 µg/kg/day had a median TSH of 3.07 mU/l at 1 month of age and normal growth.

[Maturity onset diabetes of the young: just think about it]

Maturity Onset Diabetes of the Young (MODY) is a monogenic form of diabetes with onset in patients aged less than 25 years. It is a heterogeneous disorder due to heterozygous monogenic mutations with an autosomal dominant transmission. It could represent 2 to 5% of diabetes but is often under-diagnosed. We report three different cases of MODY, two without associated abnormalities and one with renal disorder. Mutations concern genes that are directly involved in the beta-cell function. In patients with non-syndromic diabetes, more than 99% of MODY result from mutations in hepatocyte nuclear factor-1-alpha (HNF-1-alpha ; formerly MODY 3), glucokinase (MODY 2), or HNF-4-alpha (MODY 1). The symptoms manifest slowly with the absence of obesity and ketosis in most cases. MODY is usually treated by diet, oral diabetes medications or insulin. Treatment and prognosis vary depending on the genetic mutation. Clinicians should keep in mind the possibility of MODY, especially in antibody-negative youth with familial diabetes. Making a diagnosis of MODY may have important implications for the guidance of appropriate treatment, prognosis and genetic counselling.

Screening for insulinoma antigen 2 and zinc transporter 8 autoantibodies: a cost-effective and age-independent strategy to identify rapid progressors to clinical onset among relatives of type 1 diabetic patients

In first-degree relatives of type 1 diabetic patients, we investigated whether diabetes risk assessment solely based on insulinoma antigen 2 (IA-2) and zinc transporter 8 (ZnT8) antibody status (IA-2A, respectively, ZnT8A) is as effective as screening for three or four autoantibodies [antibodies against insulin (IAA), glutamate decarboxylase 65 kDa (GAD) glutamate decarboxylase autoantibodies (GADA) and IA-2A with or without ZnT8A] in identifying children, adolescents and adults who progress rapidly to diabetes (within 5 years). Antibodies were determined by radiobinding assays during follow-up of 6444 siblings and offspring aged 0-39 years at inclusion and recruited consecutively by the Belgian Diabetes Registry. We identified 394 persistently IAA(+) , GADA(+) , IA-2A(+) and/or ZnT8A(+) relatives (6·1%). After a median follow-up time of 52 months, 132 relatives developed type 1 diabetes. In each age category tested (0-9, 10-19 and 20-39 years) progression to diabetes was significantly quicker in the presence of IA-2A and/or ZnT8A than in their joint absence (P < 0·001). Progression rate was age-independent in IA-2A(+) and/or ZnT8A(+) relatives but decreased with age if only GADA and/or IAA were present (P = 0·008). In the age group mainly considered for immune interventions until now (10-39 years), screening for IA-2A and ZnT8A alone identified 78% of the rapid progressors (versus 75% if positive for ≥ 2 antibodies among IAA, GADA, IA-2A and ZnT8A or versus 62% without testing for ZnT8A). Screening for IA-2A and ZnT8A alone allows identification of the majority of rapidly progressing prediabetic siblings and offspring regardless of age and is more cost-effective to select participants for intervention trials than conventional screening.

Insulin sensitivity modulates the growth response during the first year of high-dose growth hormone treatment in short prepubertal children born small for gestational age

AIM

To study the relationship between insulin sensitivity and growth response in short children born small for gestational age (SGA) treated with growth hormone (GH).

METHODS

Randomized, open-label, 24-month intervention study in 40 short prepubertal SGA children [age (mean ± SD) 5.3 ± 1.5 years], who either remained untreated (n = 20) or were treated with GH (66 µg/kg/day; n = 20). Changes in fasting glucose, insulin, quantitative insulin sensitivity check index (QUICKI), IGF-1 and leptin after 1 and 2 years were studied.

RESULTS

Mean height SDS increased from -3.3 ± 0.7 to -2.3 ± 0.7 after 1 year, and to -1.9 ± 0.7 after 2 years of treatment. QUICKI decreased significantly (p = 0.008) in the first year of GH treatment and stabilized in the second year. Baseline QUICKI was positively associated (r = 0.40; p < 0.05) with the change in height SDS in the first year.

CONCLUSION

Higher insulin sensitivity at the start of GH therapy is associated with greater first-year growth response to GH, and could be a promising parameter in selecting prepubertal short SGA children for GH treatment. However, this finding needs to be confirmed in larger studies.

Management of familial hypercholesterolemia in children and young adults: consensus paper developed by a panel of lipidologists, cardiologists, paediatricians, nutritionists, gastroenterologists, general practitioners and a patient organization

Since heterozygous familial hypercholesterolemia (HeFH) is a disease that exposes the individual from birth onwards to severe hypercholesterolemia with the development of early cardiovascular disease, a clear consensus on the management of this disease in young patients is necessary. In Belgium, a panel of paediatricians, specialists in (adult) lipid management, general practitioners and representatives of the FH patient organization agreed on the following common recommendations. 1. Screening for HeFH should be performed only in children older than 2 years when HeFH has been identified or is suspected (based on a genetic test or clinical criteria) in one parent.2. The diagnostic procedure includes, as a first step, the establishment of a clear diagnosis of HeFH in one of the parents. If this precondition is satisfied, a low-density-lipoprotein cholesterol (LDL-C) levelabove 3.5 mmol/L (135 mg/dL) in the suspected child is predictive for differentiating affected from non-affected children. 3. A low saturated fat and low cholesterol diet should be started after 2 years, under the supervision of a dietician or nutritionist.4. The pharmacological treatment, using statins as first line drugs, should usually be started after 10 years if LDL-C levels remain above 5 mmol/L (190 mg/dL), or above 4 mmol/L (160 mg/dL) in the presence of a causative mutation, a family history of early cardiovascular disease or severe risk factors. The objective is to reduce LDL-C by at least 30% between 10 and 14 years and, thereafter, to reach LDL-C levels of less than 3.4 mmol/L (130 mg/dL).

CONCLUSION

The aim of this consensus statement is to achieve more consistent management in the identification and treatment of children with HeFH in Belgium.

Phenotypical, biological, and molecular heterogeneity of 5α-reductase deficiency: an extensive international experience of 55 patients

CONTEXT

In 46,XY disorders of sex development, 5α-reductase deficiency is rare and is not usually the first-intention diagnosis in newborn ambiguous genitalia, contrary to partial androgen insensitivity syndrome. Yet the cause of ambiguous genitalia may guide sex assignment, and rapid, precise diagnosis of 5α-reductase deficiency is essential.

OBJECTIVE

The aim of the study was to describe relevant data for clinical diagnosis, biological investigation, and molecular determination from 55 patients with srd5A2 mutations identified in our laboratory over 20 yr to improve early diagnosis.

SETTING

The study was performed at Montpellier University Hospital.

PATIENTS

We studied a cohort of 55 patients with srd5A2 gene mutations.

MAIN OUTCOME MEASURE(S)

Genetic analysis of srd5A2 was conducted.

RESULTS

Clitoromegaly (49.1%) and microphallus with various degrees of hypospadias (32.7%) were frequent phenotypes. Female external genitalia (7.3%) and isolated micropenis (3.6%) were rare. Seventy-two percent of patients were initially assigned to female gender; five of them (12.5%) switched to male sex in peripuberty. Over 72% of patients were considered for 5α-reductase deficiency diagnosis when the testosterone/dihydrotestosterone cutoff was 10. In 55 patients (with 20 having a history of consanguinity), we identified 33 different mutations. Five have never been reported: p.G32S, p.Y91H, p.G104E, p.F223S, and c.461delT. Homozygous mutations were present in 69.1% of cases, compound heterozygous mutations in 25.5%, and compound heterozygous mutations alone with the V89L polymorphism in 5.4%. Exons 1 and 4 were most affected, with 35.8 and 21.7% mutant alleles per exon, respectively.

CONCLUSIONS

In the largest cohort to date, we demonstrate a wide spectrum of phenotypes and biological profiles in patients with 5α-reductase deficiency, whatever their geographical or ethnic origins.

Growth retardation in untreated autosomal dominant familial neurohypophyseal diabetes insipidus caused by one recurring and two novel mutations in the vasopressin-neurophysin II gene

OBJECTIVE

Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI), a disorder caused by mutations in the vasopressin (AVP)-neurophysin II (NPII) gene, manifests gradually during early childhood with progressive polyuria and polydipsia. Patients are usually treated with synthetic AVP analog. If unlimited access to water is provided, prognosis is usually good even in the absence of specific treatment. In this study, we describe three families with adFNDI, in which growth failure was a prominent complaint, on the clinical and molecular level.

DESIGN/METHODS

Histories from affected and unaffected family members were taken. Height and weight of index patients were recorded longitudinally. Patients underwent water deprivation tests, magnetic resonance imaging, and genetic analysis. One mutant was studied by heterologous expression in cell culture.

RESULTS

A total of ten affected individuals were studied. In two of the three pedigrees, a novel mutation in the AVP-NPII gene was found. The index children in each pedigree showed growth retardation, which was the reason for referral in two. In these cases, water intake was tightly restricted by the parents in an attempt to overcome suspected psychogenic polydipsia and to improve appetite. Once the children were treated by hormone replacement, they rapidly caught up to normal weight and height.

CONCLUSIONS

Genetic testing and appropriate parent counseling should be enforced in adFNDI families to ensure adequate treatment and avoid chronic water deprivation, which causes failure to thrive.

Adult final height after GH therapy for irradiation-induced GH deficiency in childhood survivors of brain tumors: the Belgian experience

OBJECTIVES

The treatment of brain tumors in childhood is frequently complicated by growth retardation with a high proportion of irradiation (Irr)-induced GH deficiency (GHD) resulting in reduced adult final height (AFH) even after GH therapy (GHT). In order to optimize future GHT protocols, more information on the factors influencing the growth response to GH in these children is needed. This retrospective study evaluated AFH and influencing auxological and treatment factors of a standardized daily biosynthetic GHT in childhood survivors of brain tumors with documented GHD after brain Irr.

DESIGN AND METHODS

From the Belgian GH Registry, 57 children survivors of a brain tumor outside the hypothalamo-pituitary area with available AFH were stratified into two groups depending on cranial (C-Irr; n=25) or craniospinal (CS-Irr; n=32) Irr.

RESULTS

In the C-Irr patients, results showed an AFH of -0.8 (-2.5, 1.4) SDS (median (range)) and in the CS-Irr patients, results showed a significantly (P<0.001) lower AFH of -1.8 (-4.2, 0.0) SDS. AFH SDS corrected for mid-parental height (MPH) in the C-Irr group was -0.5 (-2.2, 0.9) and -1.5 (-3.6, 0.0) SDS in the CS-Irr group. AFH was positively correlated with age at end of tumor therapy, height SDS at start GHT, height gain SDS first year GHT, and negatively correlated with CS-Irr.

CONCLUSIONS

GHT failed to restore adult height to MPH in nearly half of Irr-induced GHD patients for brain tumor, especially those receiving CS-Irr, irradiated at a younger age or shorter at start GHT.

[Diabetic ketoacidosis: diagnosis, management, prevention]

Diabetic ketoacidosis results from relative or absolute deficiency of insulin and is a frequent metabolic emergency. It occurs in previously undiagnosed diabetes, in half of the cases in Europe, or is the consequence of a severe unbalance in a well-known diabetic patient, who, deliberately or not, does not take enough or not at all insulin. In population studies, the mortality rate in children ranges from 0,15% to 0,30%, cerebral edema accounts for 60% to 90%. Three stages are described: ketosis, ketoacidosis, ketoacidotic coma. This paper summarizes the physiopathology as well as the clinical and biological signs. It opens up an algorithm for the management of diabetic ketoacidosis and its complications and indicates prevention methods.

[Severe hypoglycemia in children and adolescents with type 1 diabetes: risks factors and management]

Hypoglycemia is one of the most common acute complications in the treatment of type 1 diabetes. It is the result of a mismatch between insulin dose, food consumed, and recent exercise. Hypoglycemia occurs more frequently in younger children and with lower HbA1c levels. Symptoms of hypoglycemia result from autonomic (adrenergic) activation and/or neurological dysfunction (neuroglycopenia). Severe hypoglycemia means that the child is having altered mental status and cannot assist in his care, is semiconscious or unconscious, or in coma--convulsions and may require parenteral therapy (glucagon or i.v. glucose). The blood glucose threshold for symptoms may be affected by antecedent hypoglycemia, duration of diabetes with decrease in neurohormonal counterregulatory responses. This phenomenon is termed hypoglycemia unawareness and is an important cause of severe hypoglycemia. Fortunately, there is absence of adverse effects of severe hypoglycemia on cognitive function in children with diabetes over 18 months, even if some controversies exist. Severe hypoglycemia is rapidly reversed by injection of glucagon 0.5 mg if < 25 kg, 1.0 mg if > 25 kg. In the hospital, intravenous infusion of glucose should be administered, e.g. glucose 10%, 2-5 mg/kg/min (1.2-3.0 ml/kg).

[Neonatal diabetes: a case of pancreatic beta cell agenesis and a 38-year follow-up of a permanent neonatal diabetes mellitus]

Neonatal diabetes, transient (TND) or permanent (PND) is a rare disease, with a reported frequency of 1/300,000. If establishing a diagnosis is quite easy, treatment remains challenging during childhood. Understanding of physiopathology increased this last decade, as many mutations in genes playing critical roles in the development of pancreas, have been described: the most common are chromosome 6q anomalies in the case of TND, and mutations in KCNJ11 and ABCC8 genes encoding the subunit of the insulin cell potassium channel in the case of PND. We report on 2 peculiar stories: the first one is the unique case of a newborn with isodisomy of chromosome 6, methylmalonic acidemia and pancreatic beta cell agenesis, who died on the 16th day of life. The second one is the longest follow-up ever described, 38-year, of a permanent neonatal diabetes mellitus without complications, except for rare micro-aneurysms, in spite of insufficient metabolic control.

Association of parathyroid adenoma and familial hypocalciuric hypercalcaemia in a teenager

OBJECTIVE

Familial hypocalciuric hypercalcaemia (FHH) is clinically characterized by mild to moderate parathyroid hormone (PTH)-dependent hypercalcaemia, autosomal dominant pattern of inheritance, and normal to frankly reduced urinary calcium excretion in spite of a high serum calcium (clearance (Ca)/clearance (Cr)<0.01). FHH has a benign course and should be differentiated from primary hyperparathyroidism. It is usually caused by a heterozygous loss-of-function mutation in the calcium-sensing receptor gene (CASR).

DESIGN

We report the case of a 16-year-old patient with hypercalcaemia and a mixed family history of parathyroid adenoma and mild hypercalcaemia. Serum calcium was 14 mg/dl with a serum iPTH of 253 pg/ml.

RESULTS

A neck 99mTc-sesta MIBI tomoscintigraphy showed a definite hyperactivity in the left upper quadrant. A surgical four-gland exploration confirmed a single parathyroid adenoma. After surgical resection of a left superior parathyroid adenoma, the patient's hypercalcemia improved but did not normalize, returning to a level typical of FHH. An inactivating mutation in exon 4 of the CASR gene, predicting a p.Glu297Lys amino acid substitution was found.

CONCLUSIONS

Thus, this 16-year old patient presented with the association of FHH and a single parathyroid adenoma. The young age of the patient and the association of parathyroid adenoma and FHH in his grandmother argue for a causal link between CASR mutation and parathyroid adenoma in this family. This case contributes to illustrate the expanding clinical spectrum of CASR loss-of-function mutations.

Atypical Rothmund-Thomson syndrome in a patient with compound heterozygous mutations in RECQL4 gene and phenotypic features in RECQL4 syndromes

We describe the natural history of the RTSII phenotype in a 7-year-old boy who developed intrauterine and postnatal growth retardation, failure to thrive and persisting diarrhoea. The growth hormone stimulation test identified an isolated growth hormone deficiency. Since infancy, the patient manifested skin lesions characterized by a very mild poikilodermic-like appearance on the cheeks only, widespread café-au-lait spots and the absence of eyebrows and eyelashes. There was no cataract. Orthopaedic and radiologic work-up identified the absence of thumb anomaly and radial head luxation and patellar hypoplasia. Neurologic, cognitive milestones and intelligence were normal. The cytogenetic work-up did not show any anomaly. Based on this clinical presentation, we carried out a sequencing analysis of the RECQL4 gene, which is responsible for Rothmund-Thomson, RAPADILINO and Baller-Gerold syndromes and found a splice site mutation (IVS10-1G>A) and a nucleotide substitution in exon 12 (L638P). The mother was identified as a carrier for the substitution in exon 12 and the father for the splice site mutation, respectively. An analysis of the transcripts focused on the RECQL4 helicase domain: in the proband only those generated from the maternal L638 allele were present. This case report emphasizes the clinical overlap between RAPADILINO and Rothmund-Thomson syndromes within a continuum phenotypic spectrum. The distinctive set of clinical signs displayed by the patient may be accounted for by his unique combination of two different RECQL4 mutations. The molecular findings provide information that enhances our comprehension of genotype-phenotype correlations in RECQL4 diseases, enables a more precise genetic counseling to the parents and facilitates a more appropriate long-term follow-up to the affected child.

Children with sickle cell disease: growth and gonadal function after hematopoietic stem cell transplantation

The aim of this study is to describe the growth, pubertal development, and gonadal function of a cohort of 30 sickle cell disease children who underwent bone marrow transplantation. They all received the standard pretransplant conditioning regimen of busulfan (14 or 16 mg/kg) and cyclophosphamide (200 mg/kg). Growth was normal both before and after transplant. Seven out of 10 girls had severe ovarian failure and requirement for estrogen replacement. Three out of 10 girls recovered some ovarian function posttransplant, with spontaneous pubertal development, menses, and 1 successful normal pregnancy. Follicle-stimulating hormone (FSH) serum levels were very high during spontaneous puberty and slowly normalized thereafter in these 3 patients. The 3 girls with ovarian function recovery differed from the 7 others by the lower busulphan dose of the conditioning regimen they received (14 rather than 16 mg/kg). All boys showed spontaneous pubertal development. However, most of them had small testis and elevated serum FSH levels, reflecting germinal epithelium damage. Testosterone level was low normal and luteinizing hormone elevated, reflecting Leydig cell insufficiency. In conclusion, 7/10 girls had complete gonadal failure and most of the boys had spontaneous puberty but germinal epithelial failure. Serum FSH levels showed important variations over time in the same patient.

Effect of 2 years of high-dose growth hormone therapy on cognitive and psychosocial development in short children born small for gestational age

OBJECTIVE AND DESIGN

Children born small for gestational age (SGA) are not only at risk for short stature, but also for neurodevelopmental and behavioral problems. In this study, we analyzed the effects of high-dose GH therapy on cognitive development and psychosocial functioning in 34 prepubertal (3-8 years) short SGA children, equally randomized into a GH-treated group (TRG) and an untreated group (UTRG).

METHODS

At start and after 2 years, children underwent standardized tests measuring the intellectual abilities (Wechsler Preschool and Primary Scale of Intelligence-Revised, or Wechsler Intelligence Scale for Children-Revised); their parents completed a standardized questionnaire evaluating psychosocial functioning (Child Behavior Checklist; CBCL).

RESULTS

At start, total IQ scores were significantly (P < 0.05) lower in the SGA group than in the general population: 32% of the SGA patients had scores below 85. After 2 years, IQ scores remained unchanged in the TRG, but increased significantly (P < 0.05) in the UTRG. After exclusion of children with developmental problems, however, no significant changes in IQ scores occurred in the UTRG as well as the TRG. At baseline, 24% (8/34) children had problematic CBCL total problems scores, equally distributed among the two groups; no significant changes in the different subscale scores occurred after 2 years.

CONCLUSION

No beneficial effect of 2 years of GH therapy on cognitive and behavioral profile could be observed in a cohort of rather young short SGA children presenting a variable degree of developmental delay and behavioral problems. Subsequent follow-up could reveal potential long-term effects of GH therapy on development and behavior.

Clinical, hormonal and imaging findings in 27 children with central diabetes insipidus

Clinical, auxological, biological and neuroradiological characteristics of 27 children with central diabetes insipidus (CDI) were retrospectively analysed. Median age at diagnosis was 8.6 years (range: 0.3-16.1 years). Final aetiologies were postsurgical infundibulo-hypophyseal impairment (n=7), cerebral tumour (n=8), Langerhans cell histiocytosis (n=3), septo-optic dysplasia (n=1), ectrodactyly ectodermal dysplasia clefting syndrome (n=1), and idiopathic (n=7). In the non-postsurgical CDI patients, major cumulative and often subtle presenting manifestations were: polyuria (n=20), polydipsia (n=19), fatigue (n=11), nycturia (n=10), growth retardation (n=9), and headache (n=9). An associated antehypophyseal insufficiency, mainly somatotropic, was documented in 11 children. All patients except one who initially had a cerebral tomography, underwent magnetic resonance imaging revealing the lack of the physiological posterior pituitary hyperintense signal. One third of the idiopathic patients initially had a thickened pituitary stalk. All patients with idiopathic CDI were intensively followed up with 3-monthly physical examination, antehypophyseal evaluation, search for tumour markers, and cerebral MRI every 6 months. In one of them the pituitary stalk had normalized after 4.3 years. In one patient Langerhans cell histiocytosis was diagnosed after 7 months of follow-up, and in another patient a malignant teratoma was found after 2.4 years of follow-up.

CONCLUSION

CDI may be the early sign of an evolving cerebral process. The association of polyuria-polydipsia should incite a complete endocrine evaluation and a meticulous MRI evaluation of the hypothalamo-hypophyseal region. A rigorous clinical and neuroradiologic follow-up is mandatory to rule out an evolving cerebral process and to detect associated antehypophyseal insufficiencies.

[The pediatric endocrinology unit: management of growth]

The unit of pediatric endocrinology takes care of children and adolescents with disorders of growth, puberty, thyroid, adrenal, pituitary or gonadal function, and also anomalies of the calcium metabolism. We have a multidisciplinary approach, including the paediatrician and the other specialists. We analyse our results locally, but also at the national and international levels. Through special patients, we try to understand different concepts, at the level of physiology or at the molecular level. A few examples will be described here and can be found in more detail in the bibliography.

[Treatment of central precocious puberty with Gonadotropin-Releasing Hormone agonist (triptorelin) in girls: breast development, skeletal maturation, height and weight evolution during and after treatment]

Central precocious puberty (CPP) is treated with GnRH analogues to stabilize secondary sexual characteristics and to prevent loss of final height (FH) due to accelerated bone maturation. However, some studies suggest that FH is not always improved and that treatment may induce excessive weight gain. We analysed data from 19 girls treated for CPP with monthly injections of 3.75 mg triptorelin. Pubertal development, bone age, height, weight and body mass index (BMI) were evaluated at start (chronological age: 7.8 +/- 1.8 yrs, mean +/- SD), at the end of treatment (10.6 +/- 1.1 yrs) and at FH (14.9 +/- 2.5 yrs). At start of treatment, breast (B) development was B3 (from 2 to 4), bone age 10.6 +/- 1.7 yrs, height 2.1 +/- 1.1 SDS and BMI 1.3 +/- 0.8 SDS. Treatment stabilized or reduced breast development and decreased bone maturation. Final height was 162.3 +/- 6.6 cm (0.0 +/- 1.1 SDS) and was comparable to predicted adult height at the start of treatment and to corrected mid-parental height. BMI SDS at the start, the end of treatment and at final evaluation were 1.3 +/- 0.8, 1.6 +/- 0.8 and 1.4 +/- 0.9 SDS. In conclusion, in our girls with central precocious puberty, treatment with GnRH agonist stabilized or decreased breast development and stabilized bone maturation, but did not increase neither final height nor weight. Aspects other than height should also be taken into account when considering treatment of children with precocious puberty.

IGF-I transcript levels in whole-liver tissue, in freshly isolated hepatocytes, and in cultured hepatocytes from lean and obese Zucker rats

BACKGROUND

The mechanisms underlying the maintenance of normal to high rates of linear growth and plasma insulin-like growth factor I (IGF-I) levels in spite of a low growth hormone secretion in obese children remain unknown. Among the animal models of early-onset obesity, obese Zucker (FA/FA) rats (which are homozygous for an inactivating missense mutation in the leptin receptor) are particularly appropriate, because their linear growth shows this growth hormone independence.

METHODS

To study the regulation of IGF-I synthesis in this model, we have established primary cultures of hepatocytes derived from 12-week-old Zucker male obese and lean rats. The rat IGF-I gene contains six exons, and alternative splicing generates different mRNAs, one of which (called IGF-1B) has been shown to be decreased by fasting. We report steady state mRNA levels for IGF-I (all transcripts) and for IGF-IB in hepatocytes after 3 days in culture, in freshly isolated hepatocytes, and in whole-liver tissue. RT-PCRs using primers specific for IGF-I or IGF-IB were performed with two different internal competitors for quantification.

RESULTS

In primary cultures of hepatocytes, the IGF-IB mRNA was increased by >50-fold (p = 0.01) in cells derived from obese animals as compared with cells from lean animals. However, these transcript levels were not significantly different when measured in freshly isolated hepatocytes or in whole-liver tissue.

CONCLUSIONS

Increased IGF-IB transcription could be an intrinsic characteristic of cultured hepatocytes harbouring leptin receptors that bear the FA mutation. However, the modulation of this characteristic by cell-cell interactions and by in vivo hormone and metabolic status remains to be studied.