Synaptic communication mediates the assembly of a self-organizing circuit that controls reproduction.

Migration of gonadotropin-releasing hormone (GnRH) neurons from their birthplace in the nasal placode to their hypothalamic destination is critical for vertebrate reproduction and species persistence. While their migration mode as individual GnRH neurons has been extensively studied, the role of GnRH-GnRH cell communication during migration remains largely unexplored. Here, we show in awake zebrafish larvae that migrating GnRH neurons pause at the nasal-forebrain junction and form clusters that act as interhemisphere neuronal ensembles. Within the ensembles, GnRH neurons create an isolated, spontaneously active circuit that is internally wired through monosynaptic glutamatergic synapses into which newborn GnRH neurons integrate before entering the brain. This initial phase of integration drives a phenotypic switch, which is essential for GnRH neurons to properly migrate toward their hypothalamic destination. Together, these experiments reveal a critical step for reproduction, which depends on synaptic communication between migrating GnRH neurons.

Marker of coxsackievirus-B4 infection in saliva of patients with type 1 diabetes.

BACKGROUND: Coxsackieviruses B (CV-B) are enteroviruses that have been reported to play a role in the pathogenesis of type 1 diabetes. Enteroviral RNA was detected in the gut mucosa of patients. The mucosal immunity is an interconnected network; therefore, the response to enteroviruses possibly present in the gastrointestinal mucosa can be reflected by specific antibodies in the saliva. In the present study, the anti-CV-B neutralizing activity of saliva samples from patients with type 1 diabetes was investigated. METHODS: Saliva samples were collected from patients and controls of 3 countries, and plasma was obtained from some of them. The anti-CV-B activity of clinical samples was determined by neutralization of the cytopathic effect induced by challenging viruses in vitro and expressed as titre value. RESULTS: Overall prevalence and levels of anti-CV-B4 activity of saliva were higher in patients (n = 181) than in controls (n = 135; P = .0002; titre values ≥ 16: odds ratio = 4.22 95% CI: 1.90-9.38 P = .0002). It has been shown that IgA1 played a role in this activity. There was no correlation between the saliva and the plasma anti-CV-B4 neutralizing activity. The neutralizing activity of saliva against CV-B1, CV-B2, CV-B3, and CV-B5 existed rarely, if at all. Increased levels of anti-CV-B4 activity were observed all along a 4 year follow-up period in patients but not in matched controls (P = .01). CONCLUSION: There is an anti-CV-B4 activity in saliva of patients with type 1 diabetes that may be a useful marker to study the role of CV-B in the pathogenesis of the disease.

Contribution of 24 obesity-associated genetic variants to insulin resistance, pancreatic beta-cell function and type 2 diabetes risk in the French population.

CONTEXT: Obesity is the major determinant of type 2 diabetes (T2D), presumably through its effect on insulin resistance. Genome-wide association studies reported many single-nucleotide polymorphisms (SNPs) that increase obesity risk and body mass index (BMI), but their impact on T2D-related traits and risk is unclear. OBJECTIVE: We aimed at analyzing the effect of 24 obesity risk alleles, separately and in combination, on variation of both insulin resistance and ß-cell dysfunction, and on T2D risk. DESIGN: We genotyped 24 obesity-associated SNPs and calculated an obesity genotype score (sum of the obesity risk alleles per individual). We analyzed the contribution of each SNP and this score to the variation of four metabolic indices: homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment of the pancreatic ß-cell function (HOMA-B), insulin sensitivity index (ISI) and insulinogenic index (II) (in up to 8050 nondiabetic French individuals) and to T2D risk (in 2077 T2D cases and 3085 controls). RESULTS: We found a highly significant effect of the obesity genotype score on increased insulin resistance adjusted for age and gender (ß=0.02; P-value=7.16 × 10(-9) for HOMA-IR). Individually, we identified nominal or significant association between increased insulin resistance and risk alleles in FAIM2, FTO, GNPDA2, MC4R, NPC1, PTER and SH2B1. Most signals, including the obesity genotype score and FTO SNP, were also associated with increased ß-cell function (ß=0.01; P-value=1.05 × 10(-6) and ß=0.04; P-value=3.45 × 10(-4), respectively). In our T2D case-control study, only the obesity genotype score and the well-known FTO locus significantly contributed to T2D risk (OR=1.03; P-value=9.99 × 10(-3) and OR=1.15; P-value=9.46 × 10(-4), respectively). Adjustment for BMI abolished all significant associations. CONCLUSIONS: Genetic predisposition to obesity contributes to increased insulin resistance and to its compensation through increased ß-cell function, and weakly increases the T2D risk. These associations are mediated by BMI.

Autoimmune polyendocrine syndrome type 1 in north-western France: AIRE gene mutation specificities and severe forms needing immunosuppressive therapies.

BACKGROUND: Autoimmune polyendocrine syndrome type 1 (APS1) has been poorly evaluated in France. We focused on the north-western part of the country to describe clinical phenotypes, especially severe forms of the disease, and AIRE gene mutations. METHODS: Clinical and immunological data were collected, and pathological mutations were identified by DNA sequencing. RESULTS: Nineteen patients were identified with APS1. Clinical manifestations varied greatly, showing 1-10 components. Mucocutaneous candidiasis, adrenal failure, hypoparathyroidism, alopecia and other severe infections were the most frequent components. Four patients had severe forms, needing immunosuppressive therapy: 2 for hepatitis; 1 for severe malabsorption, and 1 for a T cell large granular lymphocytic leukemia. These therapies were very effective but caused general discomfort. One patient died of septicemia. Four different AIRE gene mutations were identified, and a 13-bp deletion in exon 8 (c.967-979del13) was the most prevalent. There was at least one allele correlating with this mutation and alopecia occurrence (p = 0.003). No novel mutation was detected. CONCLUSION: APS1 appears to be rare in north-western France. We identified 4 cases with a severe form needing immunosuppressive therapy. The AIRE gene mutations are more like those found in north-western Europe than those found in Finland.

Childhood-onset narcolepsy, obesity and puberty in four consecutive children: a close temporal link.

Narcolepsy is a rare but disabling condition that causes excessive daytime sleepiness. Interestingly, weight gain is frequent in patients with narcolepsy and it has sometimes been described very early in the course of the disease. Here, we report four consecutive obese children who were referred to our sleep laboratory for excessive daytime sleepiness and suspected sleep apnoea syndrome. They underwent nocturnal polysomnography associated with multiple sleep latency tests. Narcolepsy was diagnosed in all children with a close temporal link between the onset of narcolepsy, obesity and puberty. Scientifically, the relationship between sleep, weight, growth rate and puberty onset is striking and merits further investigation. From the clinical point of view, narcolepsy must be investigated in obese sleepy children along with obstructive sleep apnoea. Indeed, it can be controlled with appropriate treatment but the proper diagnosis relies not only upon nocturnal polysomnography but involves the systematic use of multiple sleep latency tests.

Common genetic variation near MC4R is associated with eating behaviour patterns in European populations.

Both rs17782313 (near MC4R) and rs1421085 (FTO) polymorphisms have been consistently associated with increased risk of obesity and with body mass index (BMI) variation. An effect of both polymorphisms on satiety has recently been suggested. We genotyped rs17782313 and rs1421085 in 5764 relatives from 1109 French pedigrees with familial obesity, 1274 Swiss class III obese adults as well as in 4877 French adults and 5612 Finnish teenagers from two randomly selected population cohorts. In all subjects, eating behaviour traits were documented through questionnaires. We first assessed the association of both single nucleotide polymorphisms with BMI and then studied eating behaviour. Under an additive model, the rs17782313-C MC4R allele showed a trend towards higher percentages of snacking in both French obese children (P=0.01) and Swiss obese adults (P=0.04) as well as in adolescents from the Finnish general population (P=0.04). In French adults with familial obesity, this allele tended to be also associated with a higher Stunkard hunger score (P=0.02) and in obese children with a higher prevalence of eating large amounts of food (P=0.04). However, no consistent association of the FTO rs1421085-C allele and available eating behaviour trait was found in our studied populations. The rs17782313-C allele nearby MC4R may modulate eating behaviour-related phenotypes in European obese and randomly selected populations, in both children and adults, supporting a regulatory role of this genetic variant on eating behaviour, as previously shown for MC4R non-synonymous loss-of-function mutations. The potential effect of the obesity-associated FTO gene on eating behaviour deserves additional investigation.

A genetic study of the ghrelin and growth hormone secretagogue receptor (GHSR) genes and stature.

Growth and nutrition are interrelated and influenced by multiple genetic and environmental factors. We studied whether common variants in ghrelin and ghrelin receptor (GHSR) genes could play a role in stature variation in the general population and in families ascertained for obesity. Selected tagging SNPs in the ghrelin and GHSR genes were genotyped in 263 Caucasian families recruited for childhood obesity (1,275 subjects), and in 287 families from a general population (1,072 subjects). We performed familial testing for associations in the entire population and in a sub-set of the samples selected for a case-control study. In the case-control study for height (cases were selected from the obese cohort with mean ZH = 3.17 +/- 0.15 confidence interval (CI) versus controls with mean ZH 0.14 +/- 0.09), we found an association with a 2 base-pair intronic deletion in the GHSR gene (rs10618418) (p = 0.006, odds ratio (OR) 1.86, 95% CI [1.26;2.74] under additive model), although when adjusting for BMI, the association disappeared (p = 0.06). Individuals carrying no deletion or who were heterozygous were significantly more frequent among the tall obese population (52% vs. 36% in controls, p = 0.007, OR 1.97, 95%CI [1.22;3.18]). However, the association was not maintained after correcting for multiple testing. Familial association testing of the ghrelin and GHSR genes and their interaction testing failed to show that any combination of SNPs had any significant effect. Thus, our results suggest that common variants of the ghrelin and GHSR genes are not major contributors to height variation in a French population.

[Status of iodine nutrition of children until 1 year: consequences on the thyroid function]. / Statut en iode chez des enfants de moins de 1 an: conséquences sur la fonction thyroïdienne.

INTRODUCTION: Iodine deficiency remains a major public health problem mainly in least-developed countries but also in many industrialized countries. OBJECTIVES: The present study aimed at: (1) evaluating the status of iodine nutrition of children until 1 year in the North region of France; (2) studying risk factors for iodine deficiency; (3) evaluating relationship between iodine deficiency and thyroid disorders. PATIENTS AND METHODS: This prospective study was conducted between 1st january and 31st May 2005 in the children's hospital of Lille (North of France) and all hospitalized children until the age of 1 year were enrolled. Urinary iodine assessment was obtained for 95 (83%) of the 114 infants hospitalized during the study period and TSH value was also determined in 57 (60%) of these 114 infants. RESULTS: Median urinary iodine concentration was 328 microg/L (range: 12-1580). Twenty-four (25%) of 95 infants had a high urinary iodine excretion (urinary iodine greater than 400 microg/L). Nineteen (20%) of the 95 infants were iodine deficient (urinary iodine less than 100 microg/L): severe iodine deficiency (less than 20 microg/L; n=5; 5%), moderate iodine deficiency (20-49 microg/L; n=6; 6%), mild iodine deficiency (50-99 microg/L; n=8; 8%). No relationship was found between iodine status and the following data: age, sex, familial thyroid disease history, term and type of delivery, nutritional status, type of feeding at inclusion, chronic disease, familial socioeconomic status. TSH value was high (greater than 5 microU/mL) in 7 (12%) of the 57 infants. Only 1 of these 7 infants was iodine deficient. Only 1 of the 19 infants with iodine deficiency had a high TSH value. CONCLUSIONS: Iodine status is not optimal in our population of hospitalized children until the age of 1 year. There is no clear relationship between iodine status and thyroid function.

Single nucleotide polymorphisms in the neuropeptide Y2 receptor (NPY2R) gene and association with severe obesity in French white subjects.

AIMS/HYPOTHESIS: Genetic variants of genes for peptide YY (PYY), neuropeptide Y2 receptor (NPY2R) and pancreatic polypeptide (PPY) were investigated for association with severe obesity. SUBJECTS AND METHODS: The initial screening of the genes for variants was performed by sequencing in a group of severely obese subjects (n=161). Case-control analysis of the common variants was then carried out in 557 severely obese adults, 515 severely obese children and 1,163 non-obese/non-diabetic control subjects. Rare variants were genotyped in 700 obese children and the non-obese/non-diabetic control subjects (n=1,163). RESULTS: Significant association was found for a 5' variant (rs6857715) in the NPY2R gene with both severe adult obesity (p=0.002) and childhood obesity (p=0.02). This significant association was further supported by a pooled allelic analysis of all obese cases (adults and children, n=928) vs the control subjects (n=938) (p=0.0004, odds ratio=1.3, 95% CI 1.1-1.5). Quantitative trait analysis of BMI and WHR was performed and significant association was observed for SNP rs1047214 in NPY2R with an increase in WHR in the severely obese children (co-dominant model p=0.005, recessive model p=0.001). Association was also observed for an intron 3 variant (rs162430) in the PYY gene with childhood obesity (p=0.04). No significant associations were observed for PPY variants. Only one rare variant in the NPY2R gene (C-5641T) was not found in lean individuals and this was found to co-segregate with obesity in one family. CONCLUSIONS/INTERPRETATION: These results provide evidence of association for NPY2R and PYY gene variants with obesity and none for PPY variants. A rare variant of the NPY2R gene showed evidence of co-segregation with obesity and its contribution to obesity should be investigated further.

Influence of social class on time trends in BMI distribution in 5-year-old French children from 1989 to 1999.

AIMS: To assess the prevalence of obesity and changes in body mass index (BMI) distribution between 1989 and 1999 in 5-y-old children, and to study the influence of parental socioeconomic status on these parameters. METHODS: Two cohorts of children in the final year of nursery school (in the city of Lille, France) were enrolled in 1989 (705 children: mean age=5.6+/-0.4 y) and 1999 (1258 children: mean age=5.6+/-0.5 y). Weight and height were measured, and data about parental occupation were collected during a school medical examination. International Obesity Task Force cutoff points were used to define overweight and obesity. Parental occupation was classified into four categories. RESULTS: The prevalence of obesity increased from 1.8 to 4.9%, and the prevalence of overweight rose from 9.6 to 16.9%. Mean-difference plots allowed qualitative comparisons of the BMI distribution between the surveys: for children from the highest social classes, there was no change in BMI; for children from intermediate classes, there was a up-shift only in the upper part of the distribution with the heaviest children becoming heavier still; finally, for children from the lowest class, there was an increase in BMI across the entire population. CONCLUSIONS: This study of the changes in BMI distribution gives greater insight into the 'obesity epidemic'. Our results show the influence of an interaction between genetic and environmental factors. The increase in BMI in the upper part of the distribution suggests that this is a population with a high degree of susceptibility, whereas the increase in BMI across the whole population in the lowest social class suggests a strong influence of the environment on this group and thus the necessity of appropriate, preventive measures.

Congenital disorder of glycosylation Ib (CDG-Ib) without gastrointestinal symptoms.

We report a 7-year-old girl with hyperinsulinaemic hypoglycaemia and hepatomegaly due to congenital disorder of glycosylation (CDG) Ib without gastrointestinal symptoms. Oral mannose therapy produced clinical and biochemical normalization after 2 years of treatment.

CTLA-4 49 A/G dimorphism and type 1 diabetes susceptibility: a French case-control study and segregation analysis. Evidence of a maternal effect.

Several studies have demonstrated an association of cytotoxic T lymphocyte-associated molecule 4 (CTLA-4) (IDDM 12) alanine 17 with type 1 diabetes, but we wished to study the parental effect of CTLA-4 49 A/G dimorphism in diabetic families. The CTLA-4 exon 1 polymorphism (49 A/G), HLA-DRB1 and insulin gene (INS) variable number tandem repeats (VNTR) were analysed in 134 type 1 diabetic patients vs. 273 control subjects. The segregation analysis for transmission was carried out in 70 informative diabetic families using the transmission distortion test (TDT). All genotyping was performed by PCR-RFLP. CTLA-4 49 G allele frequency was not increased in diabetic patients compared to controls (41 vs. 38%, not significant). The distribution of GG, AG and AA CTLA-4 genotypes was similar in the two groups (13, 57 and 30% vs. 11, 54 and 35%, respectively) and was independent of HLA-DRB1 or INS VNTR polymorphism. The CTLA-4 49 G allele showed weak distorted transmission to the diabetic offspring, whereas random transmission was observed in unaffected offspring. This distortion is attributable to a maternal effect (71% compared to the 50% expected ratio; tdt = 4.8; P < 0.03). The combined transmission of maternal CTLA-4 G with HLA-DRB1*03 (90%; tdt = 6.4; P < 0.01) and VNTR class I (80%; tdt = 5.4; P < 0.02) enhanced the susceptibility effect of each marker separately. We noted a slight CTLA-4 49 G and HLA-DRB1*04 distortion of transmission shared in paternal and maternal diabetic meiosis. In non-diabetic offspring, the CTLA-4 49 A allele confers a protective effect in the presence of maternal HLA-DRB1*03 and paternal HLA-DRB1*04 alleles. Despite the absence of a positive association of the CTLA-4 49 G allele with type 1 diabetes, our segregation analysis supports the hypothesis of a modulation by CTLA-4 49 G/A dimorphism of the susceptibility conferred by maternal HLA-DRB1*03 inheritance. This potential parental effect needs to be confirmed in a larger data set.

Mutation screening of the urocortin gene: identification of new single nucleotide polymorphisms and association studies with obesity in French Caucasians.

A linkage between obesity-related phenotypes and the 2p21-23 locus has been reported previously. The urocortin (UCN) gene resides at this interval, and its protein decreases appetite behavior, suggesting that UCN may be a candidate gene for susceptibility to obesity. We localized the UCN gene by radiation hybrid mapping, and the surrounding markers were genotyped in a collection of French families. Evidence for linkage was shown between the marker D2S165 and leptin levels (LOD score, 1.34; P = 0.006) and between D2S2247 and the z-score of body mass index (LOD score, 1.829; P = 0.0019). The gene was screened for SNPs in 96 obese patients. Four new variants were established. Two single nucleotide polymorphisms were located in the promoter (-535 A-->G, -286 G-->A), one in intron 1 (+31 C-->G), and one in the 3'-untranslated region (+34 C-->T). Association studies in cohorts of 722 unrelated obese and 381 control subjects and transmission disequilibrium tests, performed for the two frequent promoter polymorphisms, in 120 families (894 individuals) showed that no association was present between these variants and obesity, obesity-related phenotypes, and diabetes. Thus, our analyses of the genetic variations of the UCN gene suggest that, at least in French Caucasians, they do not represent a major cause of obesity.